(a) List two substances that can be used in the laboratory to
(i) dry hydrogen;
(ii) remove carbon (IV) oxide from a sample of air;
(iii) convert hot copper (II) oxide to copper;
(iv) prepare zinc chloride by the action of dilute HCI.
(b)(i) Name two alloys which contain lead.
(ii) State and explain what is observed on bubbling \( \mathrm{H_2S} \) into a solution of \( \mathrm{Pb(NO)_2} \).
(iii) A metal M exists as a silvery white solid at temperatures above 18°C and as a grey solid below 18°C.
I. name the phenomenon exhibited by M.
II. What term is used to describe the temperature given as 18°C in this case?
(c)(i) Write an equation for the action of heat on each of the following compounds:
I. \( \mathrm{AgNO_3} \)
II. \( \mathrm{(NH4)_2CO_3} \).
(ii) Copy and complete the table below
| Metal |
Name of main ore |
Method of extraction |
One major use Haematite |
| — |
Haematite |
— |
— |
| — |
— |
Electrolysis of molten oxide |
— |
(a) Two substances for each purpose:
| Purpose | Substances |
|---|
| (i) Dry hydrogen | Concentrated H2SO4; fused (anhydrous) calcium chloride, CaCl2 |
| (ii) Remove CO2 from air | Sodium hydroxide solution (NaOH); soda lime |
| (iii) Convert hot CuO to copper | Hydrogen gas; carbon (II) oxide, CO (coke/carbon also acceptable) |
| (iv) Prepare ZnCl2 with dilute HCl | Zinc metal; zinc carbonate, ZnCO3 (zinc oxide also acceptable) |
(b)(i) Two alloys that contain lead: solder (tin and lead) and type metal (lead, tin and antimony).
(b)(ii) On bubbling H2S into a solution of Pb(NO3)2, a black precipitate is observed. This is lead(II) sulfide, PbS, which is insoluble and black:
\[\text{Pb(NO}_3)_2(aq) + \text{H}_2\text{S}(g) \rightarrow \text{PbS}(s) + 2\text{HNO}_3(aq)\]
(b)(iii) Metal M is tin.
- I. The phenomenon (existing in two different solid forms) is allotropy (the change from white to grey tin is known as tin pest).
- II. The temperature of 18 °C, at which one form changes into the other, is the transition temperature.
(c)(i) Action of heat:
I. On silver trioxonitrate(V):
\[2\text{AgNO}_3 \xrightarrow{\ \Delta\ } 2\text{Ag} + 2\text{NO}_2 + \text{O}_2\]
II. On ammonium trioxocarbonate(IV):
\[(\text{NH}_4)_2\text{CO}_3 \xrightarrow{\ \Delta\ } 2\text{NH}_3 + \text{H}_2\text{O} + \text{CO}_2\]
(c)(ii) Completed table:
| Metal | Name of main ore | Method of extraction | One major use |
|---|
| Iron | Haematite | Reduction in the blast furnace (with coke / carbon (II) oxide) | Making steel for construction |
| Aluminium | Bauxite | Electrolysis of molten oxide (alumina) | Making aircraft bodies and cooking utensils |
(a) Two substances for each purpose:
| Purpose | Substances |
|---|
| (i) Dry hydrogen | Concentrated H2SO4; fused (anhydrous) calcium chloride, CaCl2 |
| (ii) Remove CO2 from air | Sodium hydroxide solution (NaOH); soda lime |
| (iii) Convert hot CuO to copper | Hydrogen gas; carbon (II) oxide, CO (coke/carbon also acceptable) |
| (iv) Prepare ZnCl2 with dilute HCl | Zinc metal; zinc carbonate, ZnCO3 (zinc oxide also acceptable) |
(b)(i) Two alloys that contain lead: solder (tin and lead) and type metal (lead, tin and antimony).
(b)(ii) On bubbling H2S into a solution of Pb(NO3)2, a black precipitate is observed. This is lead(II) sulfide, PbS, which is insoluble and black:
\[\text{Pb(NO}_3)_2(aq) + \text{H}_2\text{S}(g) \rightarrow \text{PbS}(s) + 2\text{HNO}_3(aq)\]
(b)(iii) Metal M is tin.
- I. The phenomenon (existing in two different solid forms) is allotropy (the change from white to grey tin is known as tin pest).
- II. The temperature of 18 °C, at which one form changes into the other, is the transition temperature.
(c)(i) Action of heat:
I. On silver trioxonitrate(V):
\[2\text{AgNO}_3 \xrightarrow{\ \Delta\ } 2\text{Ag} + 2\text{NO}_2 + \text{O}_2\]
II. On ammonium trioxocarbonate(IV):
\[(\text{NH}_4)_2\text{CO}_3 \xrightarrow{\ \Delta\ } 2\text{NH}_3 + \text{H}_2\text{O} + \text{CO}_2\]
(c)(ii) Completed table:
| Metal | Name of main ore | Method of extraction | One major use |
|---|
| Iron | Haematite | Reduction in the blast furnace (with coke / carbon (II) oxide) | Making steel for construction |
| Aluminium | Bauxite | Electrolysis of molten oxide (alumina) | Making aircraft bodies and cooking utensils |
