(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)
- I. Reagents used in the laboratory preparation of dry chlorine gas are hydrochloric acid (HCl) and a manganese dioxide catalyst (MnO₂).
- II. The drying agent used is calcium chloride (CaCl₂) or another desiccant.
- III. The mode of collection of chlorine gas is through downward delivery into a gas jar or through upward delivery into a gas washing bottle containing the drying agent.
- (i) The equation for the preparation of chlorine gas is:
HCl(aq) + MnO₂ → Cl₂(g) + MnCl₂(aq)
- (iii) The equation to show how chlorine reacts with hot concentrated sodium hydroxide (NaOH) is:
Cl₂(g) + 2NaOH(aq) → NaCl(aq) + NaClO(aq) + H₂O(l)
(b)
- i) The main raw materials used for the extraction of iron in the blast furnace are iron ore, coke, and limestone.
- ii) The reactions taking place in the blast furnace are:
- Coke (carbon) + O₂(g) → CO₂(g)
- CaCO₃(s) → CaO(s) + CO₂(g)
- Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)
- iii) The iron obtained directly from the blast furnace is called pig iron.
- iv) Pig iron has a relatively low melting point because it contains a high amount of impurities such as carbon and silicon.
(c)
- i) SO₃ produced during the reaction is not dissolved directly in water to form H₂SO₄ because SO₃ is a highly reactive and corrosive gas. It reacts with water to produce sulfuric acid, which is a strong and hazardous acid.
- ii) H₂SO₄ is regarded as a heavy chemical because it is dense, viscous, and has a high specific gravity.
- iii) The property exhibited by tetraoxosulphate (VI) acid (H₂SO₄) in each of the following reactions is:
I. In the reaction with lead nitrate (Pb(NO₃)₂), H₂SO₄ acts as a proton donor, which means it donates hydrogen ions to the reaction.
(d)
The balanced chemical equation for the reaction between propanol (C₃H₇OH) and sodium (Na) is:
C₃H₇OH(l) + Na(s) → C₃H₇O⁻Na⁺(aq) + H(g)