(1) Seawater is slightly alkaline. This is due to the presence of HCO
3
− ions in the water.
HCO 3− (aq) + H + (aq) CO
2
(aq) + H
2
O(l) equation 2.1
(a) Use equation 2.1 and le Chatelier’s principle to explain what would happen to the concentration of HCO 3ions in the seawater if more carbon dioxide were to dissolve in the water.
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(b) The reaction represented by equation 2.1 can reach a position of dynamic equilibrium.
Explain what is meant by the term dynamic equilibrium .
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(2) Equation 4.1 represents the reaction that occurs when propene forms from propan-1-ol.
CH
3
CH
2
CH
2
OH(g) CH
3
CH=CH
2
(g) + H
2
O(g) ΔH = + 81 kJ mol
−1 equation 4.1
(a) The reaction represented by equation 4.1 can reach a position of dynamic equilibrium.
Explain what is meant by the term dynamic equilibrium .
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(b) Describe and explain the effect of the following changes on the equilibrium amount of propene produced in the reaction represented by equation 4.1
.
(i) Increasing the total pressure of the reaction system.
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(ii) Carrying out the reaction at a higher temperature.
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(f) Describe and explain what happens to the rate of the reaction represented by equation
4.1 if the pressure is increased.
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(d) The phenylethene monomer is made by passing ethylbenzene vapour over a heated catalyst at a low pressure.
Equation 2.1 represents the reaction that occurs.
C 6 H 5 CH 2 CH 3
(g) → C
6 H 5 CHCH 2 (g) + H 2 (g) Δ H = +117 kJ mol –1 equation 2.1
Describe and explain the effect of the following changes on the yield of phenylethene produced in the equilibrium represented by equation 2.1
.
(i) Carrying out the reaction at a higher temperature.
In your answer, you should use technical terms, spelled correctly.
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(ii) Carrying out the reaction at a higher pressure.
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(e) The catalyst used in the manufacture of phenylethene is in the form of a finely divided powder.
(i) Explain why the use of a finely divided powder increases the reaction rate.
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(ii) Explain how the use of a catalyst increases the reaction rate.
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