(a) Write a balanced chemical equation for each of the following reactions:
(i) ammonia gas with copper(II) oxide;
(ii) ammonia gas with oxygen gas;
(iii) aqueous potassium iodide with chlorine gas;
(iv) iron with dilute tetraoxosulphate (VI) acid;
(v) aqueous lead(II) trioxonitrate (V) with hydrogen chloride gas.
b(i) Describe briefly the process involved in the extraction of tin from tin ore.
(ii) Mention three uses of hydrogen.
(iii) State two physical properties of hydrogen.
(c) State the class of oxide to which each of the following compounds belong:
(i) Na\(_2\)O; (ii) ZnO; (iii)SO\(_2\); (iv) CO\(_2\); (v) N\(_2\)O.
a(i) 2NH\(_3\) + 3CuO → Cu + N\(_2\) + 3H\(_2\)O
(ii) 4NH\(_3\)(g) + 5O\(_2\)(g) → 4NO(g) + 6H\(_2\)O(g)
(iii) Cl₂(g) + 2 KI(aq) → 2 KCl(aq) + I₂(s)
(iv) Fe + H\(_2\)SO\(_4\) → FeSO\(_4\) + H\(_2\)
(v) Pb(NO\(_3\))\(_2\) + 2HCl → PbCl\(_2\) +2HNO\(_3\)
b(i) The process involved in the extraction of tin from tin ore
Tin extraction from its ore, primarily cassiterite (SnO₂), involves crushing, concentration (using techniques like gravity separation or flotation), smelting (heating with carbon to produce metallic tin), and finally, refining to achieve high purity.
The tin ore is first crushed and ground to a fine powder.This step aims to increase the tin content in the ore. Techniques like gravity separation, flotation, or magnetic separation are used to separate the tin-rich minerals from the gangue (waste rock). The concentrated ore is then heated with carbon in a furnace to a high temperature (around 1300-1400°C or 2375-2550°F) to reduce the tin oxide to metallic tin. The resulting impure tin is refined to achieve the desired purity for industrial applications.
(ii) Uses of hydrogen include the following:
- Hydrogen can be used in fuel cells to power vehicles.
- Hydrogen can be used to generate electricity.
- It is also used to produce "green steel".
- Hydrogen is used to extract tungsten from ore and copper from copper oxide.
- Hydrogen is used to synthesize ammonia.
- Hydrogen is used to produce nitric acid and nitrogenous fertilizers.
- Hydrogen is used to produce hydrogen chloride.
- It is used to produce water gas.
- Filling balloons.
(iii) Physical properties of hydrogen include;
- colourless,
- odourless,
- tasteless,
- highly flammable,
- It has a low density and
- low boiling and melting points.
c(i) Na\(_2\)O - basic oxide
(ii) ZnO - amphoteric oxide
(iii)SO\(_2\) - acidic oxide
(iv) CO\(_2\) - acidic oxide
(v) N\(_2\)O - neutral oxide
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