Lesson Note on Chemistry SS3 Second Term

Chemistry notes for Schools – Edudelight.com

Scheme of Work Chemistry SSS3

WEEK          TOPIC

1.   Revision/Nuclear Chemistry, Types and Nature of Radiations, Half-life as a                                       Measure of the Stability of the nucleus.

2.    Nuclear Reactions i.e Nuclear Fussion and Nuclear Fission with examples, Effect and                         applications of Radioactivity Comparison of Nuclear Reaction and Ordinary chemical                          reaction.

3.  Simple molecules and their shapes, covalent molecules e.g methane, ammonia,                                     crystalline solids – their network structure e.g diamond.

4. Metallic bonding – properties, factors affecting the formation of metals,                                          intermolecular bonding Van-der-waals forces and hydrogen bonds, comparison of all                           bond styles.

5-6.                  Metals and their compound, extraction of  metals (e.g aluminium, copper, tin and                                iron) their properties and their reaction, their uses, alloys, composition and uses.

7.                     Introduction to qualitative analysis, test for cation using H2S, NaOH and HN4OH,                             confirmatory test for the cations

8.                     Test for amono, identification or  gases. E.g CO2,SO2 and O2. Characteristics test                             for anions e,g SO42-, SO32-, CO32-, NO3.

9-10.                Volumetric Analysis, calculation based on percentage purity and impurity of                                       substances, percentage amount of the acid, or base, solubility of substances,                                     volume of gases, mole ration of acid to base.

11.                    Revision

12-13                Examinations

REFERENCE BOOK

  • New School Chemistry for Senior Secondary Schools by Osei Yaw Ababio.
  • Practical Chemistry for Senior Secondary Schools by Godwin Ojokuku
  • Outline Chemistry for Schools & Colleges by Ojiodu C. C.
  • Chemistry Pass Questions for S.S.C.E and UTME.

WEEK ONE                                                                               

TOPIC: Nuclear Chemistry

CONTENT                                                                                                              

  • Types and Nature of Radiation
  • Half-life as a measure of the stability of the nucleus.

Nuclear Chemistry is an aspect of chemistry that deal with nuclei of atoms.

Radioactivity

This is the spontaneous emission of radiation by radioactive element such as Thorium, Uranium etc.

Characteristics

  1. Spontaneously and continually emitting of radiation by radioactive element
  2. Temperature and pressure have no effect on radioactivity
  3. The radiation can pass through opaque objects
  4. It affects photographic plates
  5. It causes ionization of gases through which it passes.
  6. It causes fluorescence of certain substance
  7. It releases large amount of energy.

Types of Radiation

There are three (3) types of radiation

  1. Alpha
  2. Beta
  3. Gamma

Characteristics of Alpha-Rays

  1. they are helium in nature 42He with 4 atomic mass and 2 atomic number
  2. alpha rays are fast moving streams of positively charges
  3. they are deflected toward the negative plate in an electrostatic field
  4. they have very low penetrating power
  5. they can be absorbed/stopped by a thin sheet of paper on aluminium foil
  6. they cause fluorescence of some materials e.g zinc sulphide

Characteristics of Beta-rays

  1. they are electron in nature with a mass number of zero and charge of -1  (oe)
  2. they are fast moving  stream of electrons
  3. they can penetrate than alpha rays

Effects of Electrostatic Field on the Three Radiation

EVALUATION

  1. State two (2) properties of ά, β, and Y rays each.
  2. What do you know about radioactivity.

Detection of Radiation

The radiation can be detected by using the following devices.

  1. Geiger Miller Counts
  2. Scintillation counter
  3. Diffusion cloud chamber

HALF LIFE

The half-life of a radioactive element is the time taken for half of the actual number of atoms in a given substance or radioactive element to decay.

NUCLEAR STABILITY

The spontaneous disintegration/decay of nucleus of an element is due to its instability.

The neutron-proton ration determines the stability of an element.

This varies between unity for the lighter elements and a value of about 1.5 for the heavier element with atomic numbers around eighty.

N.B. Atoms with a neutron – protons less than 1 or greater than 1.5 tends to be unstable.

EVALUATION

  1. State two methods through which a radiation can be detected.
  2. What is half life as a measure of the stability of the nucleus

GENERAL EVALUATION

  1. Define the term  nuclear chemistry
  2. Define the term radioactivity.
  3. Explain the term radioisotopes
  4. Give an account of the uses of radioisotopes.

READING ASSIGNMENT

New School Chemistry by O.Y, Ababio pages 299-304.

WEEKEND ASSIGNMENT

  1. ____ is an example of radiation (a) Aloha (b)  Carbon (c) Uranium (d) Nucleus.
  2. Alpha particle was deflected towards negative plate while Beta deflected toward (a) Neutral plate (b) Negative plate (c) Zero plate (d) positive plate
  3. The following caused fluorescence of matter except (a) Alpha (b) Beta (c) Gamma (d) X- ray
  1. In the above diagram, Z represents (a) Alpha  (b) Beta (c) Gamma (d) Radioactive
  2. B represents ____ in the diagram above (a) Alpha (b) Beta (c) Gamma (d) Radioactive source

THEORY

  1. Find the half-life of a radio isotope element which was found to be 120g initially and later changed to 15g in 24 hours
  2. State the three main type of radiation with their properties each.

Chemistry notes for Schools – Edudelight lesson

WEEK TWO

TOPIC: NUCLEAR REACTIONS

CONTENT

  • Nuclear Fusion and Nuclear Fission with Example
  • Effects and Application of Radioactivity
  • Comparison of Nuclear Reaction and Ordinary Chemical Reactions

Nuclear Reaction

This is the spontaneous emission of radiation that involves the nuclei of radioactive element.

Nuclear Fusion

This is the process in which two or more light nuclei of elements combine together to form a heavier nucleus with release of both energy and radiation.

This process is used to produce hydrogen bomb, it is also believed to be the source of energy of the sun and stars.

Nuclear Fission

This is the process in which the nucleus of a heavy element is split into two nuclei of nearly equal mass with a release of energy and radiation. The process is used to produce atomic bomb.

EVALUATION

  1. Write short notes about
  2. Nuclear fission
  3. Nuclear fusion
  4. What is the principle of atomic bomb.

Effect of Radioactivity

  1. It causes changes in cell structure and body chemistry
    1. It leads to anemia, cancer, leukemia and genetic mutations, even death

The thick blocks of lead, iron and high density concrete can be used to get shielded from the harmful effect of radioactive rays.

 Application of Radioactivity

  1. sterilization
  2. medical uses
  3. industrial uses
  4. agricultural uses
  5. as radioactive tracers
  6. used for dating techniques

Differences Between Nuclear Reaction and Chemical Reactions

           Nuclear Reaction                                Chemical Reaction

1.  Release large amount of energy                               Release little amount of energy when                                                                                                   compared to that of nuclear reaction

2.  It involves nuclei of atoms of radioactive                It revolves the outer most electrons of

     elements                                                                 atoms.           

3. This produces different elements                          The compound produces contain the same            type of element from the reactants.

4.  It produces radiation                                              No radiation produce

5. Temperature and pressure have no effect               Both temperature and pressure have 

    on chemical reaction                                                 efects on chemical reaction

Artificial Transmutation

This is the process of transmutation of an element by bombarding it with fast moving atomic particles e.g neutrons, protons, deuterons and alpha particles.

            147N   + 10n           146C  + 11P

N.B: If the nucleus being bombarded is heavy it captures the neutron to produce an isotope of the original element

                          5927Co    +   10n                      6027CO

Binding Energy

If mathematical calculations is carried out between the parent  nucleus and daughter nuclei together with neutrons and protons on either nuclear fussion or nuclear fission, it will be found that the values are differed.

The loss of mass is known as mass defect and can be accounted for by Albert Einsteins theory of relativity.

                     E = MC2

E is energy in joule (j)

Radioactive Disintegration

This is the process by which radioactive elements decay spontaneously to release radiation.

During this process, there is usually transmutation of an atom . That is formation of daughter nucleus from the disintegrating nucleus.

Alpha Decay

When an atom losses ά particles during disintegration, the atomic number and atomic mass of the atoms is reduced by 2 and 4 respectively.  This can be represented as

                       AZK                      A-4 Z-2L    +  4 2He

                         e.g   238 U                   235Th    +  4 2He

Beta Decay

During beta decay the atomic number of the atom increases by one unit, but the atomic mass number remains unaltered.

  AK                  (2+1)L    + -1 e

   234Th                   234Pa  + -1 e

Gamma Decay

Gamma rays usually accompany the emission of either alpha or beta particles e.g

    234 Th           234Pa   + -1e + y

Radioactive Decay Series

Sometimes, if the nuclei of the new elements produced during radioactive decay is not stable, the disintegration continue until a stable nucleus is finally produced e.g. Uranium series, the thorium series and the actinium series.

M is the loss in mass in kilogram (kg) and C is the velocity of light in ms-1

GENERAL EVALUATION

  1. Define the following with an example each (a)  Nuclear Fission       (b) Nuclear Fusion
    1. (a) State two effects of radioactivity.

(b) State two differences between nuclear reaction and chemical reaction.

READING ASSIGNMENT

New School Chemistry by O. Y. Ababio pages 304-310.

WEEKEND ASSIGNMENT

  1. Examples of radioactive elements are except (a) Uranium (b) Polonium (c) Thorium (d) Oxygen
  2. 235 92U   + 1n →  141 ­ 56Ba +  92 36Kr  + 3 1 0n  

The above nuclear reaction represents (a) nuclear fission (b) nuclear fusion (c) oxidation reaction (d) esterification reaction.

  1. 238 92U             234 90Th  +   A.    In the equation, A represents (a) hydrogen (b) beryllium

(c) helium (d) oxygen

  1. Chain reaction helps during the preparation of ____ (a) Solar bomb (b) atomic bomb (c) hydrogen bomb (d) nuclear fusion
  2. 23 11Na  + 01n          2411Na The reaction represents (a) artificial radioactivity (b) Natural radioactivity (c) Nuclear fission (d) Binding energy.

THEORY

  1. Explain briefly the principle of the operation of a nuclear power plant
  2. State five (5) uses of radioactivity

Chemistry notes for Schools – Edudelight lesson

WEEK THREE

TOPIC: SIMPLE MOLECULES AND THEIR SHAPES

CONTENT

  • Covalent Molecules e.g methane, diamond, crystalline solid – their network structure e.g diamond.

Simple Molecules and their shapes

The factors that is  responsible for the shape of simple covalent molecules are

  1. sharing of electron that leads to overlapping of two atomic orbital
  2. the central atom and their valence shell electron.

Covalent Molecules

Let consider methane is an example (CH4).

The central atom is carbon with electronic configuration of IS22S2P2 which can be spined as

During the bond formation between the carbon and hydrogen, one electron is promoted from 2S to 2P2. That is IS22S12P1x2P1y2P1 or

In the molecule of methane, the carbon atom has four bond pairs of electrons in its valence shell (the octet rule is obeyed).

The C-H bond in methane are identical.  If the 2S and three 2P orbitals are hybridized to from four new orbital which are identical, this new hybrid orbitals are called SP3. That is one S and three P orbitals are combined.  The electron are negatively charged and they move to the corners of a regular  tetrahedron.  These carbon lies at the apices of the tetrahedron.

Shape of methane

EVALUATION

  1. State two (2) factors that determines the shape of simple covalent molecule
  2. Draw the shape of methane and explain its formation

Ammonia

In ammonia, NH3, the central atom is Nitrogen with configuration 1S22S2P3 or

The three unpaired electron in the 2P from the covalent bond with an election of hydrogen atom. It remain one lone pair in the outermost valence shell of nitrogen and the octect rule is satisfied.

The electron clouds of 4 pairs of electrons spaced out but not of the same shape as methane because ammonia contains one lone pair of electrons. This give ammonia a triagonal pyramidal shape.

Shape of Ammonia

Trigonal pyramidal shape of ammonia.

Crystalline Solids

  1. the crystalline solids have definite geometric shape
  2. the shape of the crystal depend on
  3. the force of attraction between the particle
  4. whether the particles are the same or different.
  5. The relative sizes of the particles if they are different.

There are 3 types of unit cell crystal based on cubic structure.

  1. Simple cubic: the particles are placed one at each corner of the cube
  2. Faced – centred cubic: the particles are located at each corner and one in the centre of     each face of the cube.
  3. Body-centred cubic: there is a particle at each corner and one at the centre of the cube.

Types of Crystalline Solids

Crystals can be grouped according to the  chemical nature of their particles

  1. covalent crystalline solid
  2. ionic crystalline solid
  3. molecular crystalline solid
  4. metallic crystalline solid.

Covalent Crystalline Solid

The best example is chemical crystal which is octahedral in shape.  The crystal lattice is build frfom a basic three- dimensional tetrahedral unit cell.  The carbon atom is lined to four other carbon atoms by covalent bonds which are directed towards the apices of a regular tetrahedron.  Thus, the unit cell is repeated several time to form a giant three dimensional molecules.

Tetrahedral unit of diamond crystal

Octahedral shape of the diamond crystal

Arrangement of the carbon atoms in the diamond

EVALUATION

  1. Explain the crystalline solid
    1. Draw the structure of

            (a)  ammonia

(b) octahedral shape of diamond

Ionic Solids

Examples are NaCl and CuSO4 crystal.  The shape of these crystals are determined according to how positive and negative ions are arranged, and according to the sizes and changes of the ions.

Molecular Crystals

There the molecules are arranged in regular patterns to give lattices.  The molecules are held together by weak intermolecular forces e.gVander Waals force, hydrogen bond, depol-depole.

Examples of the molecules are Naphthalene, iodine and dry ice crystal.

Metallic Solid

The metallic particles are held together in a crystal lattice of closely – packed sphere.

The strength of the metallic bonds varies among different metals e.g iron is more stronger than sodium and potassium.

GENERAL EVALUATON

1. Write short notes on the following

    a. ionic solid

    b. molecular crystals

    c. metallic solid

2. What are the types of attractive forces present in each of the following substances at     room temperature and pressure?

    (a) Methane                         (b) Argon     

    (c) Diamond                         (d) Water  

    (e) Aluminium

READING ASSIGNMENT

New School Chemistry by O.Y. Ababio pages 286-294.

WEEKEND ASSIGNMENT

  1. A lone pair of electron is found in (a) ammonia (b) methane (c) water (d) carbon(iv) oxide
  2. Examples of covalent molecules with linear shapes are except (a) oxygen (b) hydrogen (c) water (d) hydrogen chloride
  3. Example of compound with double bonds is (a) water (b) carbon(iv) oxide (c) methane (d) ammonia
  4. The following are types of crystalline solid except (a) covalent (b) ionic (c) metallic (d) methane
  5. The unit cells based on the cubic structure are the following except (a) simple cubic (b) complex cubic (c) body-centred cubic (d)face-centred cubic

THEORY

  1. State three (3) examples of crystalline solids with their shape
  2. Explain the following simple covalent molecules and draw their shape (a) methane (b) Water (c) carbon (iv) oxide.


Chemistry notes for Schools – Edudelight lesson

WEEK FOUR

TOPIC: METALLIC BONDING

CONTENT

  • Properties, Factors affecting the formation of metals
  • Inter molecular bonding
  • Vander-walls forces and hydrogen bonds
  • Composition and Uses.

Metallic Bonding

The atoms of metals are held together in crystal lattice by metallic bonds

Properties

  1. they are good conductors of electricity and heat
    1. high melting and boiling points
    1. they are malleable and ductile
    1. they ionize by loosing electrons

Factors affecting the formation of metal strength

The Valence Electrons

Intermolecular Bonding

This is the type of chemical bonding which can be found in some molecular solid. Examples of intermolecular forces are

  1. vander walls forces
  2. Hydrogen force/bond

Vander Waal Forces: this is the  weak attractive forces that exist between the molecule.

Importance of  Vander waal forces

  1. it is important in the liquefaction of gases
  2. it is used in the formation of molecular lattices like iodine and naphthalene crystals.

EVALUATION

  1. State the properties of the following bonds.

a. metallic bond            b. Vander waal

  1. Give the diagram of a named metallic element (bonding diagram)

Hydrogen Bonding

Hydrogen bonding occur when hydrogen is covalently bonded with strongly electronegative element e.g nitrogen, fluorine, oxygen.

These electronegative elements pall the shared pair of electrons in the covalent bonds toward themselves.  Thus it results in dipole where the hydrogen is positive and the electronegative element is negative.

An electrostatic attraction set up when the positive pole of one molecule attract the negative pole of another molecule.

NB: The attractive force that exist between the two poles is called hydrogen bond.

Example of hydrogen bond

  1. Hydrogen fluoride molecules
  • Water molecules (ice crystal)

NB: There is covalent bond in a molecule of water while hydrogen bond is formed in molecules of water.

Use

It helps in the formation of water, alkanols and some organic acid molecules

GENERAL EVALUATION

  1. Use diagram to differentiate between a molecule of water and molecules of water
  2. State the molecules of a substance with strongest hydrogen bond.
  3. Explain simple cubic structure

READING ASSIGNMENT

New School Chemistry by O.Y Ababio pg 294-298

WEEKEND ASSIGNMENT

  1. An example of intermolecular bonding is (a) Vander wall (b) metallic (c) ionic (d) covalent
  2. Both metallic substance and electrovalent compound are similar because (a) Both dissolve readily in water. (b) they have low melting point. (c) they can conduct electricity. (d) they have low boiling point.
  3. The dotted line in an intermolecular bond stands for ____ (a) oxygen (b) hydrogen bond (c) ionic bond (d) covalent bond
  4. Vander Wall force of attraction can be grouped as (a) Strongest force (b) hydrogen bond

(c) weakest force (d) ionic bond.

  1. Metallic bond can easily be identified by the presence of (a) positive charge              (b) negative charge            (c) neutral charge (d) double bonds.

THEORY

  1. State the type of chemical bond found in the following substances
  2. Magnesium
  3. Sodium chloride
  4. Ammonium chloride
  5. Molecules of hydrogen fluoride
  6. A molecule of hydrogen
  7. State four properties of the following  chemical bonds:
  8. Electrovalent bond
  9. covalent bond
  10. dative bond
  11. hydrogen bond
  12. metallic bond

WEEK FIVE

TOPIC: PRELIMINARY PREPARATION

Metals are found mixed with earthy materials as ores. Ores are often

  1. concentrated and
  2. converted to oxides before extraction

Concentration of the ore can be  done by any of the following ways:

  1. washing away the earthy materials
  2. Froth- flotation (zinc ore): The ore is agitated (churned up ) with oil and water to form a froth. The froth is removed by blowing air through it
  3. By passing magnetic ores through a magnetic separator.  The ore will be deflected while the non-magnetic or partially magnetic part of the ore will move on.

Roasting in Air

The ore is roasted in air to convert to an oxide. There is no need to roast if the ore is already an oxide.

Principle of Extraction of  metals

Those metals which are found in a combined state can be extracted through electrolysis or by chemical and thermal methods.  The selected method of extraction of any given metal depends on the stability of the ore.  The stability of the ore depends on the reactivity of the metal.

MetalReactivityMost common oreMethod of extraction
K Na Ca Mg    Very reactiveChloridesElectrolysis of fused hydroxides and chlorides
Chlorides & TrioxocarbonatesElectrolysis of fused chlorides
Al Zn Fe Sn Pb  Moderately reactiveOxides CO32- and SulphideRoasting of CO32- & sulphides to form oxides reduction of oxides by C of CO
  sulphides
Roasting in air
Heating in air
Cu Hg   Ag Au    Least reactive      Free element    Mined as free elements  

EVALUATION

  1. Explain froth floatation
  2. State two ways of concentrating an ore

SODIUM

OCCURRENCE

Sodium occurs as NaCl (rock salt), NaNO and Na2CO3.is often known as Chile saltpeter because it is found abundantly in Chile. It also occurs as borax and in complex trioxosilicates (iv) found in clay soil.

Extraction:  It is extracted by electrolysis of fused NaCl using the Downs cell. The cathode is a steel cylinder.  Fused NaCl (mp:801oc) is put in the cell where it is heated to keep it molten. CaCl2 is often added to lower the melting point of NaCl to about 600oC. Sodium and chloride are the products.

As the electrolysis progresses, the molten Na collects in the cathode chamber where it gets to the top and is collected through a pipe. A hood guides the gaseous chloride at the anode for collection.

At the cathode: Na+  + e-                 Na(s)     (Reduction )

At the anode : Cl-                Cl + e-             (Oxidation)

                       Cl  + Cl                 Cl2 (q)

Overall electrolysis reaction.

2Na+(g)  + 2Cl-(i)                   2Na(s)  + Cl2(g)

Physical Properties

  1. Silvery solid with metallic luster
  2. Flaots on water (density of 0.98)
  3. very malleable
  4. melting point of 97oC (Low for a metal)
  5. Good conductor of heat and electricity.

EVALUATION

  1. Write the cathodic and anodic half cell equations in the electrolysis of fused NaCl
  2. What is the function  of CaCl2 introduced into the electrolytic cell during the electrolysis above.

Chemical Properties

  1. Reaction with air

4Na (s)   + O2(g)            2Na2O(s)

Na2O(s)  + H2O(g)            2NaOH (aq)

2NaOH (aq) + CO2(g)           Na2CO3(s)  + H2O (i)

Sodium tarnishes easily when exposed to air due to presence of oxygen.

Sodium is stored in paraffin oil, toluene or naphtha to prevent its oxidation by air. In excess air the reaction can be represented as follows:

2Na (g) + O2(g)                     Na2O2(g)

2. Combination reaction: with H2, Cl2,S,P (with non-metals except Boron,carbon & Nitrogen)

2Na(s)  + H2(g)       2NaCl(g)

2Na(s) + Cl2(g)           2NaCl(g)

2Na(s) + S(g)           Na2S(s)

3Na(s)  + P(g)              Na2P(s)

In Hg

       Na(s)  + Hg (l)                               Na/Hg(l)

With water: it reacts violently with cold water giving out a lot of heat and liberating hydrogen gas.

  2Na + H2O           Na2O + H2

  2Na + 2H2O           2NaOH  + H2

4. With acid:

      2Na(s)  + 2HCl(aq)             2NaCl(aq)  + H2O

NB: The reaction is explosive and extremely dangerous

5.  with ammonia

     2Na(s)   + 2NH3 (g)                      2NaNH2(s)  + H2 (g)

Test for sodium ions

Flame test: Na compounds give a golden yellow colour for non-luminous flame.

Note: Potassium gives a lilac (pale purple) flame which looks common (deep red) when viewed through a blue gas.

USES OF SODIUM

  1. It is used in manufacturing important compounds such as tetraethyl lead (Iv) .(Pb(C2H5)4
  2. Sodium vapour lamps (orange-yellow light) are used to light high ways and airports
  3. it is used in liquid form as a coolant in nuclear reactors
  4. Can be used as a reducing  agent in combination with ethanol or sodium amalgam.
  5. Can be sued in the extraction of titanium to reduce titanium tetrachloride to the metal.

Compound of Sodium  The following are compounds of sodium: Na2O, Na2O2, NaOH, NaCl, Na2SO4, NaNO3, NaCO3.

SODIUM TRIOXOCARBONATE (Na2CO3)

Na2CO3 exists.

  1. As soda ash in the anhydrous state
  2. As a monohydrate, Na2CO3.H2O.
  3. As a decahydrate (more often) Na2CO3.10H2O called washing soda

The laboratory preparation follows the three equations below:

a.    2NaOH(aq)  + CO2(g)           Na2CO3.   +     H2O(l)

b.   Na2CO3(aq)    + H2O  +  CO2(g)              2NaHCO3 (s)

c.    2NaHCO3(s)                 NagCO3 + H2O(g)  + CO2(g)

The NaHCO formed as a white ppt is filtered off, washed and heated to give he anhydrous Na2CO3. Na2CO3 is prepared industrially using the Solvay process.

SOLVAY PROCESS – INDUSTRIAL PREPARATION
A concentrated sodium chloride solution is saturated with NH3 gas to produce ammoniacal brine this is allowed to fall into the top of a large tower.  As the solution passes through a series of baffle-plates (baffles) it react with CO2 which is forced up the tower under pressure.

  1. NH3(aq)  + CO2(g)   + H2O              NH4HCO3(aq)
  2. NH4HCO3(aq) + NaCl(aq)              NaHCO3(s)   + NH4Cl (aq)

The NaHCO3(aq)  is filtered, washed  and heated to yield anhydrous NaCO3, steam and CO2. the CO2 is used again in the tower.

  1. 2NaHCO3(s)    heat      Na2CO3(s)  + H2O  + CO2 (g)

The soda ash (anh. Na2CO3) can be dissolved in hot H2O and re-crystallized as washing soda

  1. Na2CO3(s)  + 10HsO (l)

The economic importance of the process.

  1. The CO2 required in the process is obtained by heating CaCO3 in a lime kiln.

            CaCO3(s)                    CaO(s)  + CO2(g)

  • CaO(s)   + 2 NH4Cl(aq)                      CaCl2(aq)   + H2O (l)

            The NH3 is recycled. The raw materials are NaCl, CaCO3. The only waste product is CaCl2.

GENERAL EVALUATION

  1. Write an equation to show the reaction of sodium with air.
  2. Explain briefly the economics of the Solvay process.
  3. Explain the reaction of sodium with cold water.
  4. Explain what happens to the following when they are exposed to the atmosphere;    

(a) washing soda (b) caustic soda pellets

WEEKEND ASSIGNMENT

  1. Which of these is not an alkali? (a) Sodium hydroxide (b) Potassium hydroxide (c) Aqueous ammonia (d) none of the above
    1. Which compound is added to fused NaCl to lower its melting point? (a)CaCO3 (b) CaCl2

(c) Ca(OH)2  (d) Ca(NO3)2

  • NaHCO3 is also called? (a) Chalk (b) Baking powder (c) Lime (d) Slaked lime 
    • What is the colour of sodium flame (a) white (b) red (c) black (d) green
    • Sodium reacts explosively with cold water to liberate (a) Hydrogen (b) CO2 (c) O2 (d) Na2O.

THEORY

  1. (a) Explain the Solvay process

            (b) What is the function of NH3 in the process

  • Why is it necessary to concentrate the ore before extraction of any metal?

READING ASSIGNMENT
New School Chemistry by O.Y Ababio pages 419-442.

Chemistry notes for Schools – Edudelight lesson

WEEK SIX

TOPIC: METALS AND THEIR COMPOUND

CONTENT

  • Aluminum
  • Occurrence

Aluminum can be obtained as Kaolin, Al2O3.2SiO3.2H2O, cryolite. Na3AlF6, Corundum Al2O3 and mica K2O.Al2O3.6SiO2.

NB: the main source of aluminum is bauxite Al2O3.2H2O

Extraction

Aluminum can be found in clay and rocks, but due to their high silica content, they can not be used for extraction of aluminum. The extraction of aluminum is carried out by electrolysis of bauxite.

The extraction proceeds in two stages.

1. Purification of Bauxite

Bauxite is first heated with caustic soda solution under pressure to form soluble sodium aluminate(III)

Al2O3 + 2NaOH + 3H2O                    2NaAl(OH)4

The impurities, iron III oxide and trioxosilicates (iv) can be filtered off as a sludge.

The filterate contains aluminate (III) and then seeded with aluminum hydroxide crystals to induce precipitation of aluminum hydroxide.

NaAl(OH)4       Al(OH)3  + NaOH

The Al(OH)3 is then filtered off, washed, dried and heated strongly to yield pure aluminium oxide or alumina while the NaOH is concentrated and used again.

2Al(OH)3          Al2O3  + 3H2O

Chemistry of the Reaction

Alumina  consist of aluminum and oxygen ions

At the Cathode

The aluminum ions gain three electrons each at the cathode to deposit as metallic aluminum.

Al3+  + 3e          Al

At the Anode

The oxygen ions donate two electrons each to form atomic oxygen, which then pair off to form gaseous molecules.

O2-                  O + 2e-

O  + O             O2

Overall Reaction

4Al3+ 6O2-                 4Al + 3O2

Physical Properties

  1. It is silvery white solid
  2. Aluminum has density of 2.7glcm3
  3. It is very malleable and ductible
  4. It can be rolled into a foil
  5. It has melting point of 660o                  
  6. It is a very good conductor of  heat and electricity
  7. It has moderate tensile strength but high in alloys.

Chemical Properties

1. Reaction with air

    4Al + 3O2                  2Al2O3(s)

    2Al + N2                     2AlN(s)

2. Reaction with non-metals e.g Sulphur, Nitrogen phosphorus, carbon and halogen

               2Al + 3Cl2             2AlCl3

3. Reaction with Acids

    2Al + 6HCl                      2AlCl3 + 3H2

    2Al + 6H2SO4                   Al2(SO4)2 + 6H2O + 3SO2

NB: Aluminum can not react with either dilute HNO3 or conc. HNO3 due to formation of a          protective layer of aluminum oxide.

4.  Reaction with Alkali

       2Al + 2NaOH  + 6H2O   2NaAl(OH)4  + 3H2

5.  Reaction with iron III oxide

      2Al + Fe2O3                   Al2O3 + 2 F3.

Test for Aluminum Ions

Add drops of sodium hydroxide solution to the unknown salt solution. Formation of a white    gelatinous precipitate which dissolve in an excess of sodium hydroxide solution indicates   the presence of aluminum ions.

Add a few drops of aqueous NH3 solution to the unknown salt solution. The formation of   white gelatinous precipitate which dissolve in excess of aqueous NH3 confirms the   presence of aluminum ion .

        Al3+  + 3OH                Al(OH)3

USES

  1. Aluminium is used in making cooking utensil
  2. It is sued in making overhead electric cables
  3. It is used in making alloys e.g duralumin
  4. Aluminium powder suspended in oil is used in paints mirrors and cars.

Iron

Occurences

Iron is usually found as haematite, Fe2O3, magnetite Fe3O4, iron pyrites, FeS2, siderite or spathic iron ore FeCO3 and limonite Fe2O3.H2O.

Iron is the second most abundant metal in the earth’s crust after aluminium. It is also present in clay haemoglobin and chlorophyll in plants.

Extraction

The iron e.g haematite is first roasted in air to produce iron (III) oxide.

The iron (III) oxide is then mixed with coke and lime stone and heated to a very high temperature in a blast furnace.

In the lower part of the furnace, the white hot coke is oxidized by the oxygen in the hot air to liberate carbon (Iv) oxide. C + O2          CO2.

The CO2 change to carbon(ii) oxide at the top of the furnace and then react with iron (III) oxide and reduce it to iron

Fe2O3 + 3CO        2F3 + 3CO2

The limestone present decomposes at high temperature to yield calcium oxide, which then combine with the silicon(Iv) oxide, impurity, to form calcium trioxosilicate (iv)

Ca CO3           CaO + CO2

SiO2 + CaO + CaSiO3

The molten iron sinks to the bottom of the furnace and is tapped off. It is run into moulds where it sets as pig iron.

Physical Properties

  1. Iron is silvery solid with luster
  2. It has relative density of 7.9
  3. It is very ductile
  4. It has high tensile strength
  5. It has melting point of 1530oC
  6. It is good conductor of heat and electricity

NB: It can be magnetized easily.

Chemical Properties

Reaction with Air

  4Fe + 3O2 + 2xH2O           2Fe2O3.XH2O

Reaction with steam

   3Fe + 4H2O         Fe3O4 + 4H2

Reaction with non-metals e.g sulphur, chlorine,

 2Fe + eCl2                  2FeCl3

   Fe + S                     FeS

Reaction with Acid

Fe + H2SO4                FeSO4 + H2

NB: No reaction is observed when conc. HNO3 is added to iron.

Uses

NB: Fe2+ is used as confirmatory  test for oxidizing agent in the laboratory.

Cast iron is used for making objects which do not require high tensile strength e.g stove, cookers, lamp post radiator etc

Cast iron is used for making nails, chains, iron rods, and sheets of iron, agricultural implements etc.

GENERAL EVALUATION

  1. What is the main source of Aluminium in nature?
    1. Using a diagram and equations, explain how pure Aluminium is extracted from the above source.
    1. With the aid of a diagram and the equation of the reaction, show how you would mend a broken iron rod by the thermit process.

READING ASSIGNMENT

New School Chemistry by Osei Yaw Ababio, pages 442 – 478.

WEEKEND ASSIGNMENT

  1. Aluminium reacts readily with all common mineral acids except

A. HNO3 B. HCl  C. H2SO4 D. H3PO4

  1. The great affinity of aluminium for oxygen at high temperatures is employed in the

A. electrolytic process  B. thermit process  C. Haber process  D. lead chamber process

  1. Aluminium materials should not be exposed to alkalis because aluminium is A. basic B. acidic  C. an oxidizing agent  D. a reducing agent
  2. Wrought iron is the    A. purest form of iron B. most brittle form of iron C. most impure D. form of iron containing no carbon
  3. Which one is the most common iron ore? A. Magnetite B. Haematite C. Carnallite D. Dolomite

THEORY

  1. (a) Write the electronic configuration of iron?

            (b) Iron forms the iron(II) ion, Fe2+ and the iron(III) ion, Fe3+.

  • Write the electronic configurations of these ions.
  • Which of them is more stable?
  • Give reason for your answer.
  1. Explain why iron but not aluminium corrode easily on exposure to air despite the fact that aluminium is above iron in the electrochemical series.

WEEK SEVEN

TOPIC: INTRODUCTION TO QUALITATIVE ANALYSIS

  • Introduction to Qualitative Analysis

Test for carbons using H2S, NaOH and NH4OH, Confirmatory Test for the cat ions.

Introduction to Qualitative Analysis

Qualitative analysis involves examination of colour, flame test, effect of heat and confirmatory test for cat ion and anions.

Cations are metallic ions e,g Ca2+, Pb2+, Al3+, Cu2+, Fe2+ , Fe3+, etc

Rules in Qualitative Analysis

  1. Your test solution should not be diluted too much
    1. Use only small quantity of reagents

Examination of colour and physical state of specimen

            Substance                          colour                                 physical state

1.          Sulphur                              yellow                                 solid

2.         Copper(ii)oxide       black                                  solid

3.         Iodine                               dark brown              solid

4.         Nitrogen iv oxide              reddish brown                     gas

5.         Mercury                            white                                   liquid

Flame test

  1. Deep green colour of flame indicate the presence of copper
  2. Deep yellow colour indicate the presence of sodium
  3. Brick red indicate calcium.

EVALUATION

  1. State ten (10) examples of cations
  2. Give the colour of the following substance.
  3. Distilled water
  4. Iron filling
  5. Manganese(iv) oxide
  6. Benzoic acid.

Test for Cations

The Cations are Ca2+, Zn2+, Al3+, Pb2+, Fe2+. Fe3+, Cu2+, NH4 +

Test for Ca2+

        Test                   Observation                    Inferences

Sample + H2O                           dissolve to give a                      soluble

                                                Colourless solution

+ NaOH in drop                        white powdery precipitate       

in excess                                  insoluble in excess                    Ca2+ present

soln + NH3 soln                         No noticeable reaction             Ca2+ present

Test for Zn2+

Sample + H2O                           dissolve in water to                  soluble

                                                Give a colourless solution

Soln  + NaOH in                        white gelatinous precipitate     Zn2+, pb2+,

Drop in excess                          soluble in excess                      Al3+ may be present

Soln  +  NH3 soln                      white gelatinous precipitate    

In drop

In excess                                 ppt soluble in excess                Zn2+ present

                                                Test for Al3+

Sample +H2O                            dissolve in water to give           soluble

                                                a colourless solution

soln + NaOH

in drop                                     white gelatinous precipitate     Zn2+,pb2+ Al3+ may be

in excess                                  soluble in excess                      present

Soln + NH3OH                          white gelatinous ppt

In drops

In excess                                 insoluble in excess                     Al3+ or pb2+

                                                Test for Pb2+

Sample + H2O                           dissolve in water to give            soluble

                                                Colourless solution

Soln + NaOH

In drop                                     White gelatinous ppt                Zn2+,Pb2+, Al3+

In excess                                 soluble in excess                       may be present

Soln+ NH3 soln

In drop                                     white gelatinous ppt                 Al3+ or Pb2+

In excess                                 insoluble in excess                    may be present

Soln + dil HCl                           white ppt                                   Pb2+ present

Ppt + heat                                ppt dissolve when hot and

                                                Reappear when cool                    Pb2+ present

Soln + K2CrO4                          yellow precipitate                                   Pb2+ present

Test for Fe2+

Test                     Observation                            Inferences

Sample + H2O               dissolve in water                                      soluble

Soln +NaOH soln

In drops                       dirty green gelatinous ppt                        Fe2+ present

In excess                     insoluble in excess                               

Soln +NH3 in                 Dirty green  gelatinous

Drop                             precipitate                                                Fe2+ present

In excess                     insoluble in excess

Test for CU2+

Test                   Observation                            Inference

Sample +H2O                dissolve in water                                  soluble

Soln +NaOH in

Drops                           Blue gelatinous ppt      

In excess                     insoluble in excess                                Cu2+ present

Soln+NH3 in drop          pale blue gelatinous ppt

In excess                     soluble in excess to give a

                                    Deep blue solution                                Cu2+ present

Test for NH4+

Test                   Observation                            Inferences

Sample + H2O               dissolve in water to give a

                                    Colourless solution                               soluble

Soln +NaOH                  No ppt, but effervescence occur

In drop + warm             with libration of colourless gas

                                    with choking smell

Gas + moist                   It turns moist red litmus paper            Alkaline gas

Litmus paper                blue.

Gas  + con HCl              It gives white fumes with con HCl        NH3 gas from NH4+

GENERAL EVALUATION

  1. Give the common reagents used for confirmatory test for cations.
  2. State the colour of the solution when the sample that contains the following dissolve in water:

a. Fe 2+             b. Cu 2+             c. Fe 3+

WEEKEND ASSIGNMENT

  1. The following  give white gelatinous precipitate in NaOH except? (a) Al 3+ (b) pb2+ (c) CU 2+

(d) Zn2+

  • One of the following gives ‘pop’ sound when contact with lighted splint. (a) O2 (b) H2 (c ) NH3

(d) CO2

  • Example of cations that gives gas during its confirmatory test is (a) SO32- (b) SO42-  (c) CO32-

(d) NH4+

  • Deep green colour of flame indicate the presence of (a) sodium (b) calcium    (c) copper (d) iron
  • The only alkaline gas that changes moist red litmus paper to blue is (a)NH3    (b) HCl (c) NaOH (d) NH4OH

THEORY

  1. Explain the confirmatory test for the following cations
  2. State the flame test for the following :

a. Calcium         b. Copper          c. sodium            d. iron

READING ASSIGNMENT

School Chemstry by O.Y Ababio pages 165 – 183

Practical chemistry by R. I. Makanjuola pages 31-36.

Practical Chemistry for Schools and Colleges by Godwin O. Ojokuku pages 30 – 98.

WEEK EIGHT

Test for Anions,

Identification of gases e.g CO2, SO2 and O2.

Characteristics test for anions e.g SO42-,SO32-,CO32-,NO-3, Cl, etc.

The anions are negatively change ions examples of anions are SO42-,SO32-,CO32-,S2- etc.

Identification of Gases

            Gases               identification

1.          H2                    It gives a ‘pop’ sound when the gas is contact with a lighted splint.

2.         O2                    It rekindles a glowing splint.

3.         CO2                  It is colourless and odourless. It turns lime water milky.

4.         Cl2                    A green wish yellow gas, it turns moist iodide paper black.

5.         SO2                  Colourless gas with irritating smell. It turns damp blue litmus paper to red. That

                                    is acidic gas.

EVALUATION

  1. State two (2)  examples of anions with their gases.
  2. Identify Cl2 and NH3 gases.

Test For Anions

Test for SO42-

Test                             Observation                                          Inferences

Sample +H2O                dissolve in water                                  soluble

Soln +Bacl2+                 white ppt                                              SO42-, SO32-,CO32-

Dil HCl                         ppt insoluble                                        SO42-, confirmed.

Soln + dil HCl               No visible reaction                               SO32-,CO32-,S2- are absent

Soln + Bacl2                  white precipitate                                  SO42-, confirmed

Test for SO32-

Soln+Bacl2                    white precipitate

+ dil HCl                       dissolve in dil HCl                                 SO32- or CO32-

soln+acidified               decolourise the purple

soln  of KMnO4 colour to colourless                              SO32- confirmed

soln +                            the orange colour change                     SO32- confirmed

acidified K2Cr2O7            to green (reducing property)   


Test for CO32-

Soln+dil HCl                 Effervescence occurred and a             SO32-,CO32-, S2-

                                    Colourless gas is librated                     may be present

Gas+litmus paper          it changes moist blue litmus paper        acidic gas

                                    To red.

Gas + lime water           The gas turned lime                             gas is CO2 from CO32-

                                    Water milky.

Test for S2-

Test                             Observation                                          Inferences

Soln + dil HCl               A colourless gas evolved                       H2S gas from S2-

                                    With rotten egg smell

Gas +KMnO4 soln          purple colour is decolourised

                                    With a deposit of sulphur                    S2- present

Test for Cl

Soln + dil HNO3                        No visible reaction                   SO32- or CO3 are absent

Soln + AgNO3                           white precipitate                      Cl- present

GENERAL EVALUATION

  1. Give the common reagents for confirmatory test of anions
  2. State how you would confirm/test for NO3-
  3. Name three gases that are colourless and acidic to litmus.
  4. Sodium chloride and silver trioxonitrate(V) crystals are separately soluble in water to give colourless solutions. Explain what happens when their solutions are mixed together.

READING ASSIGNMENT

School Chemstry by O.Y Ababio pages 165 – 183

Practical Chemistry by R. I Makanjuola pages 27-33.

Practical Chemistry for Schools and Colleges by Godwin O. Ojokuku pages 30 – 98.

WEEKEND ASSIGNMENT

  1. Brown ring test is used to confirm (a) S2- (b)NO3- (c) SO42- (d) SO32-
  2. The presence of SO32- change the colour of acidified K2Cr2)7 from (a) green to red    (b) purple to colourless  (c) orange to green  (d) green to orange
  3. A greenish yellow gas that change moist iodide paper black is (a) Cl2   (b) SO2 (c) H2  (d) O2
  4. Sometimes in the presence of  conc HsSO4, copper turning and heat NO3- gives (a) brown ring reaction  (b) pure brown fume   (c ) reddish brown   (d) effervescence        
  5. The gas that turns lime water milky is (a) H2 (b) SO2 (c) NH3 (d) CO2.

THEORY

  1. State the colour of these solutions a. KMnO4 b. K2Cr2O3 c. HOBr d. CuSO4.5H2O e. Ca(OH)2
    1. Carry out the following exercises on sample K. add about 10cm3 of distilled water to K in a test tube. Divide the solution into four.
    1. To the 1st portion add NaOH  drop wise and in excess.
    1. To the 2nd portion add NH3 solution drop wise and then in excess.
    1. To the 3rd portion, add it drops of BaCl2 follow by the addition of dil HCl
    1. To the 4th portion, add dil HCl follow by the addition of BaCl2.

Record your observation and inferences then name the salt K.

WEEK NINE

TOPIC: VOLUMETRIC ANALYSIS

CONTENT

  • Calculation Based on Percentage Purity and Impurity of substances.
    • Percentage/amount of water of crystallization,
    • Molar mass of the acidic base
    • Solubility of substances
    • Volume of gases
    • Mole ratio of acid to base

Volumetric Analysis

Volumetric analysis involves acid base titration.

Mole Ratio

Mole ratio is the ratio of the reacting species.  This determines the ratio of the acid that would react with the base.

Examples are

1.          H2SO4  +  2NaOH                           Na2SO4 + 2H2O

CaVa   =  ½

CbVb

2.         2HCl +  Na2CO3              2NaCl +H2O + CO2

            CaVa =    2

            CbVb       1

EVALUATION

  1. What is volumetric analysis
  2. Give the ratio of the reaction species in the following chemical reactions

a.   CaCO3 + 2 HCl             CaCl2     +   H2O    +   CO2

b.  KHCO3 + 2HCl              KCl +      H2O    +    CO2

Calculation Involving Titration                                       

1.  Mole Ratio

A is a solution of an acid hydrogen chloride .B is a solution of sodium trioxocarbonate(iv) containing 0.05 mole per dm3 solution A was titrated against 25cm3 of solution B, using methyl orange as indicator during the process, the following data were obtained.

Burette reading (cm3)             Rough               1st                           2nd                         3rd

Final burette reading (cm3)      24.65               48.95               24.30               24.30

Initial burette reading (cm3)    0.00                 24.65               0.00                 0.00

Volume of acid used (cm3)        24.65               24.30               24.30               24.30.

  1. Calculate the average titre value
    1. Calculate the concentration of the acid in moldm3.
    1. Calculate the concentration of the acid in g/dm3.

The equation of the reaction

NaCO3 + 2HCl                   2NaCl +H2O + CO2

Solution

1. Average titre value =     24.30 + 24.30 + 24.30

                                                      3

                                  = 24.30cm3

2. Concentration of A in moldm3

    from                                          

                     CaVa = Na

                     CbVb    Nb

                        Ca x 24.30    =  2

                        0.05 x 25           1

            Ca =  0.05 x 25 x 2

                        24.30

            Ca = 0.103moldm3.

                        OR

From no  of mole  = Conc. In moldm-3  X vol/dm3

No of moles = 0.05 x  25

                                  1000

equation of the reaction.

Na2CO3  + 2HCl                  2NaCl + H2O + CO2

  1. :  2

1 mole of Na2CO3 react with 2 moles of HCl

:. 0.00125 mole of Na2CO3 will require 0.00123 x 2 of HCl

:. No of mole of A = 0.0025 mole

From conc of A in moldm-3 =  No of mole

                                                 Volume in dm3

                                          =  0.0025       ×  10000

                                           24.30

                                          1000

                                            0.0025 x 1000

                                                24.30.

                                          = 0.103moldm3

3. Concentration of A in g/dm3

From:- conc in g/dm3 = conc in moldm-3 x molar mass

Molar mass of HCl = 1 + 35.5  = 36.5 g/mol.

:. Conc in g/dm3 = 0.103 x 36.5

                          = 3.76g/dm3

PERCENTAGE PURITY AND IMPURITY

During the titration process of an impure acid or base is titrated only the pure part of either acid or base react with the base or acid.  Therefore the percentage (%) purity or impurity can be calculated.

% purity   = Conc in g/dm3 of pure solution     X     100

                    Conc in g/dm3 of impure solution         1

% impurity =  conc of impure – conc of pure   X  100

                        conc in g/dm3 of impure                 1

Mass of pure substance = Conc of pure in moldm-3 x Molar Mass

Mass of impurity  = Conc of impure – pure

Example

A is a solution of 020mole of HCl per dm3. B is a solution of an impure  sodium trioxocarbonate(iv) containing 3.0g per 250cm3.

a.  Calculate the

(i)   percentage purity of A

(ii)  percentage impurity of A

Va = 20.40cm3     Vb = 25.00cm3

The equation of reaction

Na2CO3 + 2HCl                   2NaCl + H2O + CO2

(Na = 23 C= 12 O = 16 H = 1, Cl = 35.5)

Solution

    CaVa  = na

     CbVb    nb

     0.20 x 20.40   =  2

      25 x cb              1

Cb = 0.20 x 20.40 x 1

                 25 x 2

Cb = 0.0823 moldm3

Conc in g/dm3 of pure

From

Conc in g/dm3 = Moldm3 x molar mass

Molar mass of Na2CO3 = 2(23) + 12 + 3 (16)

Molar mass of Na2CO3 = 106g/mol

:. Conc in g/dm3 of pure = 0.082 x 106

                                     = 8.692 g/dm3

Conc of impure Na2XO3

250 cm3 dissolve  3.0g of Na2CO3

1 cm3 dissolves    3.0   X 1000

                             250

                           = 12.0g/dm3

1. :. % purity  =  Conc of pure X 1000

                          Conc of impure      1

                   =  8. 69     X  100

                          12              1

                   = 72.4%

% impurity  =  Conc of impure – pure  X        100

                           Conc of impure                   1

% impurity  =    12 – 8.6g X      100

                             12                1

                   = 27.6%

PERCENTAGE AMOUNT OF WATER OF CRYSTALLIZATION

Water of crystallization in the wager given off when an hydrated salt is heated or exposed to the atmosphere

Hydrated salt does not contain water

Amount of water of crystallization is calculated as follows:

    Conc of anhydrous           =    moalr mass of anhydrous

    Conc of hydrated                   molar mass of hydrated

Percentage Water of Crystallization is calculated as follows:

%  water of crystallization =    Hydrated – Anhydrous    X         100

                                                                    Hydrated                  1

Example

Solution A is a solution of hydrogen chloride acid containing 0.095 moldm3 of solution.

B is a solution of hydrated salt Na2CO3. XH2O containing 3.94g which was made up to 250cm3 of solution with distilled water

Va = 29.00cm3, Vb = 25.00cm3.

Calculate the

I.  value of X

II. percentage of water of crystallization.

Equation of the reaction

Na2CO3.XH2O  + 2HCl                     2NaCl + H2O + H2O + CO2

Solution

i. Value of x

From

     CaVa      =    Na                   CaVa       =     2

     CbVb           Nb                CbVb            1

   0.095 x 29    =  2

    Cb x 25            1

Cb =  0.095 x 29 x 1

          25 x 2.

Cb = 0.0550moldm3

Conc in g/dm3 of Na2CO3 = moldm-3  x m.m

Molar mass of Na2CO3 = 2 (23) + 12 + 3(16)  = 106 g/mol

Conc in g/dm3 = 0.055 x 106  = 5.83 g/dm3

Conc in g/dm3 of hydrated:

                       Mass     X  1000

                       Volume        1

Conc in g/dm3  =  3.94 x 1000

                                  250

                        = 15.8g/dm3

   Conc of anhydrous     =  molar mass of anhydrous

 Conc of hydrated              molar mass of hydrated.

           5.83     =   106

         15.76          106 x 18

(106 x 18x) 5.83  = 106 x 15.76

106 + 18x  =  106 x 15.76

                            5.83

106 + 18x = 286. 55

18x = 286.55 – 106

18x = 180.55

x =  180.55

           18.

x = 10

The salt is Na2CO3.10H2O

READING ASSIGNMENT

Practical Chemistry by Makanjuola pages 1-15.

New School Chemistry by Osei Yaw Ababio pages 165 – 183

Practical Chemistry for Schools and Colleges pages 100 – 170

GENERAL EVALUATION

  1. What is volumetric analysis
  2. Name five  apparatus used in volumeric analysis.
  3. Define the following terms;   a. Indicator  b. Buffers  c. pH scale

WEEKEND ASSIGNMENT

  1. C + water give colourless solution (a) c is a soluble salt (b) c is partially dissolve in water (c) c is a filterate (d) c is a residue
  2. ____ is the apparatus use to convert vapor into liquid during distillation. (a) conical flask (b) distillation column   (c) lie-big condenser (d) round bottom flask
  3. X which fumes in most air can be suitably stored (a) under paraffin or naphtha (b) In a white bottle (c) inside a corked conical flask (d) inside a burette.
  4. The observation in bubbling SO2 into acidified KMnO4 solution is (a) The solution turns to green   (b) the solution becomes decolourized  (c) no visible reaction (d) the solution turns steam
  5. The two substances that can give both H2 and ZnSO4 when added to H2SO4 are: (a) Magnesium and Zinc (b) Magnesium and CuO (c) Sodium and NaOH (d) iron and copper

THEORY

  1. State what would observe on
  2. mixing Zinc dust with CuSO4 solution
  3. adding concentrated HNO3 to freshly prepared FeSO4 solution
  4. A salt sample was suspected to be either Na2CO3 or NaHCO3. A student who was required to identify it, tested a portion for solubility in water and for effects on litmus paper.
  5. What was the observation in each case?
  6. State the reason why the student’s procedure was unsuitable.
  7. Describe briefly how you would have identified the salt.

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