GCSE OCR Gateway Chemistry: Combined Science 6.2 Reversibility & Equilibrium: When a reversible reaction is le

Question

When a reversible reaction is left in a closed system, an equilibrium is reached.

(a) Look at the equation.

2NO₂(g) ⇌ N₂O₄(g)

It shows the equilibrium between NO₂(g) and N₂O₄(g).

(i) Fig. 17.1 shows how the reaction rate of the forward and backward reactions change as the equilibrium is reached.

Describe how Fig. 17.1 shows that the equilibrium has been reached.

(ii) Fig. 17.2 shows how the concentrations of NO₂(g) and N₂O₄(g) change as the equilibrium is reached.

Describe how Fig. 17.2 shows that the equilibrium has been reached.

(b) Each of the equations, A–E, shows a reversible reaction.

A  N₂(g) + O₂(g) ⇌ 2NO(g)            ΔH = +180 kJ/mol
B  2SO₂(g) ⇌ 2SO₃(g)                     ΔH = +196 kJ/mol
C  2H₂(g) ⇌ H₂(g) + I₂(g)               ΔH = +110 kJ/mol
D  N₂(g) + 3H₂(g) ⇌ 2NH₃(g)         ΔH = -92 kJ/mol
E  CH₄(g) + H₂O(g) ⇌ CO(g) + 3H₂(g) ΔH = +206 kJ/mol

ΔH shows the energy change of the forward reaction.

(i) Write the letter, A–E, of one equation where more product is formed when the temperature is decreased.

(ii) Write the letter, A–E, of one equation where the amount of product is unchanged when the pressure is increased.

(iii) Write the letter, A–E, of one equation where more product is formed when either the temperature is increased or when the pressure is decreased.

When a reversible reaction is left in a closed system, an equilibrium is reached - OCR Gateway - GCSE Chemistry: Combined Science - Question 17 - 2021 - Paper 10

Worked Solution & Example Answer:When a reversible reaction is left in a closed system, an equilibrium is reached - OCR Gateway - GCSE Chemistry: Combined Science - Question 17 - 2021 - Paper 10

Describe how Fig. 17.1 shows that the equilibrium has been reached.

Describe how Fig. 17.2 shows that the equilibrium has been reached.

Write the letter, A–E, of one equation where more product is formed when the temperature is decreased.

Write the letter, A–E, of one equation where the amount of product is unchanged when the pressure is increased.

Write the letter, A–E, of one equation where more product is formed when either the temperature is increased or when the pressure is decreased.

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