(a)(i) Describe briefly the laboratory preparation of hydrogen gas from the action of steam on iron.
(ii) Write the equation for the reaction in (a)(i).
(iii) List three methods for the industrial preparation of hydrogen gas.
(b) Consider the following reaction equation:
\(\mathrm{CO(g)} + 2\mathrm{H}_{2(g)} \qquad \mathrm{CH}_3\mathrm{OH}_{(g)} + 201\) kJmol-J
Predict the effect of each of the following factors on the position of equilibrium:
(i) decrease in temperature;
(ii) increase in pressure;
(iii) increase in concentration of \(\mathrm{CO}_{(g)}\).
(c) (i) Define condensation polymerization.
(ii) Name two condensation polymers.
(iii) Write the formula of ethylethanoate.
(d) (i) Define the term allotropy.
(ii) Name two crystalline allotropes of carbon.
(iii) State one use of each of the allotropes named in (d)(ii).
(e) State two differences between nitrogen (I) oxide and oxygen.
(a)(i) Place iron filings in a hard-glass (combustion) tube and heat strongly. Pass steam (from heated water) over the red-hot iron; the hydrogen produced is led away by a delivery tube and collected over water.
(a)(ii) \[ 3\text{Fe} + 4\text{H}_2\text{O} \rightleftharpoons \text{Fe}_3\text{O}_4 + 4\text{H}_2 \]
(a)(iii) Industrial preparation of hydrogen: (1) electrolysis of acidified water or brine; (2) steam reforming of natural gas/hydrocarbons; (3) passing steam over red-hot coke (water gas, then the water-gas shift).
(b) The forward reaction is exothermic and reduces the number of gas molecules (3 \(\to\) 1):
- (i) Decrease in temperature: equilibrium shifts forward (right), giving more methanol.
- (ii) Increase in pressure: equilibrium shifts forward (right), giving more methanol.
- (iii) Increase in [CO]: equilibrium shifts forward (right), giving more methanol.
(c)(i) Condensation polymerization is a polymerization in which monomers (each with two functional groups) join together with the elimination of a small molecule such as water.
(c)(ii) Nylon and terylene (polyester).
(c)(iii) \( \text{CH}_3\text{COOC}_2\text{H}_5 \)
(d)(i) Allotropy is the existence of an element in two or more different forms in the same physical state.
(d)(ii) Diamond and graphite.
(d)(iii) Diamond is used in cutting/drilling tools and as an abrasive; graphite is used as a lubricant and as electrodes (pencil lead).
(e) (1) Nitrogen(I) oxide has a faint sweet smell whereas oxygen is odourless. (2) Burning sulphur continues to burn in oxygen but is extinguished in nitrogen(I) oxide (N2O does not support the combustion of a feebly burning substance).
(a)(i) Place iron filings in a hard-glass (combustion) tube and heat strongly. Pass steam (from heated water) over the red-hot iron; the hydrogen produced is led away by a delivery tube and collected over water.
(a)(ii) \[ 3\text{Fe} + 4\text{H}_2\text{O} \rightleftharpoons \text{Fe}_3\text{O}_4 + 4\text{H}_2 \]
(a)(iii) Industrial preparation of hydrogen: (1) electrolysis of acidified water or brine; (2) steam reforming of natural gas/hydrocarbons; (3) passing steam over red-hot coke (water gas, then the water-gas shift).
(b) The forward reaction is exothermic and reduces the number of gas molecules (3 \(\to\) 1):
- (i) Decrease in temperature: equilibrium shifts forward (right), giving more methanol.
- (ii) Increase in pressure: equilibrium shifts forward (right), giving more methanol.
- (iii) Increase in [CO]: equilibrium shifts forward (right), giving more methanol.
(c)(i) Condensation polymerization is a polymerization in which monomers (each with two functional groups) join together with the elimination of a small molecule such as water.
(c)(ii) Nylon and terylene (polyester).
(c)(iii) \( \text{CH}_3\text{COOC}_2\text{H}_5 \)
(d)(i) Allotropy is the existence of an element in two or more different forms in the same physical state.
(d)(ii) Diamond and graphite.
(d)(iii) Diamond is used in cutting/drilling tools and as an abrasive; graphite is used as a lubricant and as electrodes (pencil lead).
(e) (1) Nitrogen(I) oxide has a faint sweet smell whereas oxygen is odourless. (2) Burning sulphur continues to burn in oxygen but is extinguished in nitrogen(I) oxide (N2O does not support the combustion of a feebly burning substance).
