2ND TERM SS3 CHEMISTRY SCHEME OF WORK AND NOTE

SECOND TERM E-LEARNING NOTE

SUBJECT: CHEMISTRY CLASS: SSS 3

Scheme of Work

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 SO₄^2-, SO₃^2-, 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

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

Types of Radiation

There are three (3) types of radiation

• Alpha
• Beta
• Gamma

Characteristics of Alpha-Rays

• they are helium in nature ⁴₂He with 4 atomic mass and 2 atomic number
• alpha rays are fast moving streams of positively charges
• they are deflected toward the negative plate in an electrostatic field
• they have very low penetrating power
• they can be absorbed/stopped by a thin sheet of paper on aluminium foil
• 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.

• Geiger Miller Counts
• Scintillation counter
• 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.

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

• Write short notes about

1. Nuclear fission
2. Nuclear fusion

• What is the principle of atomic bomb.

Effect of Radioactivity

1. It causes changes in cell structure and body chemistry
2. 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

• sterilization
• medical uses
• industrial uses
• agricultural uses
• as radioactive tracers
• 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   ⁶⁰₂₇C_O

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

^A_ZK   ^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
2. (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.

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

   (c) helium (d) oxygen

4. Chain reaction helps during the preparation of ____ (a) Solar bomb (b) atomic bomb (c) hydrogen bomb (d) nuclear fusion
5. 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

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

• the crystalline solids have definite geometric shape
• the shape of the crystal depend on

1. the force of attraction between the particle
2. whether the particles are the same or different.
3. 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
2. 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.

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
2. high melting and boiling points
3. they are malleable and ductile
4. 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

• it is important in the liquefaction of gases
• 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

2. 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

• 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.

5. 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
   1. Magnesium
   2. Sodium chloride
   3. Ammonium chloride
   4. Molecules of hydrogen fluoride
   5. A molecule of hydrogen
2. State four properties of the following chemical bonds:
   1. Electrovalent bond
   2. covalent bond
   3. dative bond
   4. hydrogen bond
   5. 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.

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:801^oc) 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  Cl_{2 (q)}

Overall electrolysis reaction.

2Na+(g) + 2Cl-(i)  2Na_(s) + Cl_2(g)

Physical Properties

1. Silvery solid with metallic luster
2. Flaots on water (density of 0.98)
3. very malleable
4. melting point of 97^oC (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) Na₂CO_3(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) + O_2(g)  Na₂O_2(g)

    

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

   2Na_(s) + H_2(g) 2NaCl_(g)

   2Na_(s) + Cl_2(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) + 2NH_{3
   (g)}   2NaNH_2(s) + H_{2 (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) + CO_2(g)   Na₂CO₃. + H₂O_(l)

   b.  Na₂CO_3(aq) + H₂O + CO_2(g) 2NaHCO_{3 (s)}

   c.  2NaHCO_3(s) NagCO₃ + H₂O_(g) + CO_2(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) + CO_2(g) + H₂O NH₄HCO_3(aq)
   2. NH₄HCO_3(aq) + NaCl_(aq) NaHCO₃(s) + NH₄Cl _(aq)

   The NaHCO_3(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 Na₂CO_3(s) + H₂O + CO₂ (g)

    

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

   1. Na₂CO_3(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) + CO_2(g)

   1. CaO(s) + 2 NH₄Cl(_aq)  CaCl_2(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
   2. Which compound is added to fused NaCl to lower its melting point? (a)CaCO₃ (b) CaCl₂

      (c) Ca(OH)₂ (d) Ca(NO₃)₂

   3. NaHCO₃ is also called? (a) Chalk (b) Baking powder (c) Lime (d) Slaked lime
   4. What is the colour of sodium flame (a) white (b) red (c) black (d) green
   5. 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

   1. 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.

    

    

   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.

O^2-  O + 2e-

O + O  O₂

Overall Reaction

4Al₃+ 6O^2- 4Al + 3O₂

Physical Properties

• It is silvery white solid
• Aluminum has density of 2.7glcm3
• It is very malleable and ductible
• It can be rolled into a foil
• It has melting point of 660o
• It is a very good conductor of heat and electricity
• 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 F_3.

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

• Iron is silvery solid with luster
• It has relative density of 7.9
• It is very ductile
• It has high tensile strength
• It has melting point of 1530oC
• It is good conductor of heat and electricity

NB: It can be magnetized easily.

Chemical Properties

Reaction with Air

4Fe + 3O₂ + 2xH₂O 2Fe₂O₃.X_H2O

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?
2. Using a diagram and equations, explain how pure Aluminium is extracted from the above source.
3. 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

2. 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

3. Aluminium materials should not be exposed to alkalis because aluminium is A. basic B. acidic C. an oxidizing agent D. a reducing agent
4. 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
5. 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⁺.

1. Write the electronic configurations of these ions.
2. Which of them is more stable?
3. 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
2. 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.
   1. Distilled water
   2. Iron filling
   3. Manganese(iv) oxide
   4. 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₊

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

   (d) CO₂

3. Example of cations that gives gas during its confirmatory test is (a) SO₃^2- (b) SO₄^2-  (c) CO₃^2-

   (d) NH₄⁺

4. Deep green colour of flame indicate the presence of (a) sodium (b) calcium  (c) copper (d) iron
5. 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 SO₄^2-,SO₃^2-,CO₃^2-,NO^-3, Cl^–, etc.

The anions are negatively change ions examples of anions are SO₄^2-,SO₃^2-,CO₃²-,S^2- 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 SO₄^2-

Test Observation  Inferences

Sample +H₂O dissolve in water soluble

Soln +Bacl₂+ white ppt  SO₄^2-, SO₃^2-,CO₃^2-

Dil HCl ppt insoluble  SO₄^2-, confirmed.

Soln + dil HCl No visible reaction SO₃^2-,CO₃^2-,S^2- are absent

Soln + Bacl₂ white precipitate SO₄^2-, confirmed

Test for SO₃^2-

Soln+Bacl₂ white precipitate

+ dil HCl dissolve in dil HCl SO₃^2- or CO₃^2-

soln+acidified decolourise the purple

soln of KMnO₄  colour to colourless SO₃^2- confirmed

soln + the orange colour change SO₃^2- confirmed

acidified K₂Cr₂O₇  to green (reducing property)  

Test for CO₃^2-

Soln+dil HCl Effervescence occurred and a SO₃^2-,CO₃^2-, S^2-

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 CO₃^2-

Water milky.

Test for S^2-

Test Observation  Inferences

Soln + dil HCl A colourless gas evolved H₂S gas from S^2-

With rotten egg smell

Gas +KMnO₄ soln  purple colour is decolourised

With a deposit of sulphur S^2- present

Test for Cl^–

Soln + dil HNO₃  No visible reaction SO₃^2- 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 NO^3-
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) S^2- (b)NO^3- (c) SO₄^2- (d) SO₃^2-
2. The presence of SO₃^2- 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 NO^3- 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
2. 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 1^st portion add NaOH drop wise and in excess.
   2. To the 2^nd portion add NH₃ solution drop wise and then in excess.
   3. To the 3^rd portion, add it drops of BaCl2 follow by the addition of dil HCl
   4. To the 4^th 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 1^st 2^nd 3^rd

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
2. Calculate the concentration of the acid in moldm³.
3. 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 = 25.00cm^3.

   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
      1. mixing Zinc dust with CuSO₄ solution
      2. adding concentrated HNO₃ to freshly prepared FeSO₄ solution
   2. 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.
      1. What was the observation in each case?
      2. State the reason why the student’s procedure was unsuitable.
      3. Describe briefly how you would have identified the salt.