Question detail
Explain how to measure the equilibrium constant for a reaction at a given temperature.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
A-level practical endorsement and required practical activities
Question
Explain how to measure the equilibrium constant for a reaction at a given temperature.
Answer
To measure the equilibrium constant (Kc), first establish the balanced equation for the reaction. Then, measure the concentrations of the reactants and products at equilibrium. Substitute these values into the formula Kc = [products] / [reactants], where the concentrations are raised to the power of their coefficients in the balanced equation. This answer is anchored to A-level required practical activities.
Explanation
To measure the equilibrium constant (Kc), first establish the balanced equation for the reaction. Then, measure the concentrations of the reactants and products at equilibrium. Substitute these values into the formula Kc = [products] / [reactants], where the concentrations are raised to the power of their coefficients in the balanced equation. is the best answer because it directly supports the AQA A-Level Chemistry objective to required practical 8: measure an equilibrium constant. This reasoning is anchored to A-level required practical activities in A-level practical endorsement and required practical activities, and it separates required practical from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Misunderstanding Equilibrium Constants
Students often confuse the equilibrium constant expression with the reaction quotient, leading to incorrect calculations.
To fix this, remember that the equilibrium constant (Kc) is calculated using the concentrations of products raised to their coefficients divided by the concentrations of reactants raised to their coefficients at equilibrium. For example, for the reaction aA + bB ⇌ cC + dD, the formula is Kc = [C]^c[D]^d / [A]^a[B]^b. Substitute the equilibrium concentrations into the formula, perform the calculations, and ensure to include units of mol/dm³ for concentrations. Keep the correction anchored to A-level required practical activities and the objective: Required practical 8: measure an equilibrium constant.
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