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Hydrogen gas is made by the reaction between methane, CH₄, and steam - OCR Gateway - GCSE Chemistry - Question 21 - 2022 - Paper 1
Question 21
Hydrogen gas is made by the reaction between methane, CH₄, and steam. The reaction reaches a dynamic equilibrium. This is the equation for the reaction. CH₄(g) + ... show full transcript
Worked Solution & Example Answer:Hydrogen gas is made by the reaction between methane, CH₄, and steam - OCR Gateway - GCSE Chemistry - Question 21 - 2022 - Paper 1
Step 1
State what is meant by a dynamic equilibrium.
Answer
A dynamic equilibrium refers to a state in a reversible reaction where the rates of the forward and backward reactions are equal. In this state, the concentrations of reactants and products remain constant over time, although both reactions continue to occur. This equilibrium can be disturbed by changes in conditions such as concentration, temperature, or pressure, leading to a shift in the balance.
Step 2
State and explain what happens to the position of the equilibrium.
Answer
When the temperature of the equilibrium mixture is increased in an endothermic reaction, the position of the equilibrium shifts to favor the formation of products. This is in accordance with Le Chatelier's Principle, which states that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change. Thus, increasing the temperature will drive the reaction forward to absorb the added heat, leading to an increase in the concentration of products.
Step 3
Suggest why a pressure of 30 atmospheres is used.
Answer
A pressure of 30 atmospheres is used to maximize the yield of hydrogen gas due to the volume of gases involved in the reaction. Since there are fewer moles of gaseous products (4 moles of gaseous products) compared to reactants (2 moles of gaseous reactants), increasing the pressure shifts the equilibrium to the right, favoring the production of hydrogen. Additionally, higher pressure can enhance the rate of reaction, making the process more efficient.