WAEC 2020
(a) In the laboratory preparation of dry chlorine gas, state the: I. reagents used; II. drying agent III. the mode of collection.
(i) Write the equation for the preparation of chlorine gas. (iii) Write an equation to show how chlorine reacts with hot concentrated NaOH.
(b)i). Name the main raw materials used for the extraction of iron in the blast furnace. (ii) Write the equations of the reactions taking place in the blast furnace.
(iii) What is the name given to the iron obtained directly from the blast furnace? (iv) State why the iron named in 4(b)(iii) have a relatively low melting point?
(c) The following equation represents one of the reaction steps involved in the contact process: 2SO\(_2\) + O\(_2\) ⇌ 2SO\(_3\) ΔH = -395.7 kJ mo-l
(i) Why is the SO\(_3\) produced during the reaction not dissolved directly in water to form H\(_2\)SO\(_4\)? (ii) Why is the H\(_2\)SO\(_4\) regarded as a heavy chemical? (iii) State the property exhibited by tetraoxosulphate (VI) acid in each of the following reaction equations.
I. Pb(NO\(_3\))\(_2\) + H\(_2\)SO\(_4\)→ PbSO\(_4\) + 2HNO\(_3\) (d) Write a balanced chemical equation for the reaction between propanol and sodium
(a) In the laboratory preparation of dry chlorine gas, state the: I. reagents used; II. drying agent III. the mode of collection.
(i) Write the equation for the preparation of chlorine gas. (iii) Write an equation to show how chlorine reacts with hot concentrated NaOH.
(b)i). Name the main raw materials used for the extraction of iron in the blast furnace. (ii) Write the equations of the reactions taking place in the blast furnace.
(iii) What is the name given to the iron obtained directly from the blast furnace? (iv) State why the iron named in 4(b)(iii) have a relatively low melting point?
(c) The following equation represents one of the reaction steps involved in the contact process: 2SO\(_2\) + O\(_2\) ⇌ 2SO\(_3\) ΔH = -395.7 kJ mo-l
(i) Why is the SO\(_3\) produced during the reaction not dissolved directly in water to form H\(_2\)SO\(_4\)? (ii) Why is the H\(_2\)SO\(_4\) regarded as a heavy chemical? (iii) State the property exhibited by tetraoxosulphate (VI) acid in each of the following reaction equations.
I. Pb(NO\(_3\))\(_2\) + H\(_2\)SO\(_4\)→ PbSO\(_4\) + 2HNO\(_3\) (d) Write a balanced chemical equation for the reaction between propanol and sodium
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Correct Answer: Option
Explanation:
(a) (i) Conc HCL and MnO\(_2\) KMnO\(_2\) (II) Conc H\(_2\)SO\(_4\) (III) Downward delivery / upward displacement of air.
(ii) 16HCL + 2KMnO\(_4\) --> 2MnCl\(_2\) + 2KCl + 8H\(_2\)O5Cl\(_2\)
OR
MnO\(_2\) + 41HCI --> MnCl\(_2\) 2H2O\(_2\) + CI\(_2\) (III) 3Cl\(_2\) + 6NaOH --> 5NaCl + NaClO\(_3\) + 3HO\(_2\)
(b) (i) - Hematite: - Coke: - Limestone (ii) C + CO\(_2\) --> C + CO\(_2\) --> 2CO Fe\(_2\)O\(_3\) ⇒ Fe + 3CO\(_2\) . CaCO\(_3\) --> CaO + CO\(_2\)
CaO + SiO\(_2\) --> CaSiO\(_3\)
(iii) Pig Iron (iv) because it contains impurities not pure. (
c) (i) the dissolution of ŠO\(_3\) in water is highly exothermic, mist of acid droplets would be formed. (ii) it is produced on a large scale: - it is required by many industries as a raw material ; it is in high demand by other industries. (iii) I. Acting as a displacement/precipitating agents; ii. Acting as an Oxidizing agent
(d) 2CH\(_3\)CH\(_2\)CH\(_2\)OH + 2Na --> 2CH\(_3\)CH\(_2\)CH\(_2\)ONa + H\(_2\); OR 2CH\(_3\) H\(_7\)OH + 2Na --> 2CH\(_2\)H\(_7\)ONa + H\(_2\)
(a) (i) Conc HCL and MnO\(_2\) KMnO\(_2\) (II) Conc H\(_2\)SO\(_4\) (III) Downward delivery / upward displacement of air.
(ii) 16HCL + 2KMnO\(_4\) --> 2MnCl\(_2\) + 2KCl + 8H\(_2\)O5Cl\(_2\)
OR
MnO\(_2\) + 41HCI --> MnCl\(_2\) 2H2O\(_2\) + CI\(_2\) (III) 3Cl\(_2\) + 6NaOH --> 5NaCl + NaClO\(_3\) + 3HO\(_2\)
(b) (i) - Hematite: - Coke: - Limestone (ii) C + CO\(_2\) --> C + CO\(_2\) --> 2CO Fe\(_2\)O\(_3\) ⇒ Fe + 3CO\(_2\) . CaCO\(_3\) --> CaO + CO\(_2\)
CaO + SiO\(_2\) --> CaSiO\(_3\)
(iii) Pig Iron (iv) because it contains impurities not pure. (
c) (i) the dissolution of ŠO\(_3\) in water is highly exothermic, mist of acid droplets would be formed. (ii) it is produced on a large scale: - it is required by many industries as a raw material ; it is in high demand by other industries. (iii) I. Acting as a displacement/precipitating agents; ii. Acting as an Oxidizing agent
(d) 2CH\(_3\)CH\(_2\)CH\(_2\)OH + 2Na --> 2CH\(_3\)CH\(_2\)CH\(_2\)ONa + H\(_2\); OR 2CH\(_3\) H\(_7\)OH + 2Na --> 2CH\(_2\)H\(_7\)ONa + H\(_2\)