Question detail
A gas mixture has a total pressure of 900 kPa. If the mole fraction of gas A is 0.3, what is the partial pressure of gas A?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Equilibrium constant Kp for homogeneous systems (A-level only)
Question
- A. 270 kPa
- B. 300 kPa
- C. 330 kPa
- D. 360 kPa
Answer
270 kPa
Explanation
The correct option is 270 kPa. 270 kPa is the best answer because it directly supports the AQA A-Level Chemistry objective to calculate mole fractions and partial pressures. This reasoning is anchored to Kp and partial pressure (A-level only) in Equilibrium constant Kp for homogeneous systems (A-level only), and it separates mole fraction 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
Incorrect Calculation of Partial Pressure
Students often confuse the calculation of partial pressure with total pressure, leading to incorrect values.
To calculate the partial pressure of a gas in a mixture, use the formula: P_partial = X_gas * P_total, where X_gas is the mole fraction of the gas. For example, if the mole fraction of gas A is 0.3 and the total pressure is 100 kPa, then P_partial = 0.3 * 100 kPa = 30 kPa. Ensure to clearly identify the mole fraction and total pressure before performing the calculation. Keep the correction anchored to Kp and partial pressure (A-level only) and the objective: Calculate mole fractions and partial pressures.
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