Question detail
What is the concentration in mol/dm³ of a solution containing 2 moles of solute in 1 dm³ of solution?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Amount of substance
Question
- A. 2 mol/dm³
- B. 1 mol/dm³
- C. 0.5 mol/dm³
- D. 4 mol/dm³
Answer
2 mol/dm³
Explanation
The correct option is 2 mol/dm³. Use Concentration in mol/dm3: concentration = moles / volume. The worked result is 2 mol. 2 mol/dm³ is the best answer because it directly supports the AQA A-Level Chemistry objective to use standard form, appropriate units and significant figures in mole calculations. This reasoning is anchored to The mole and the Avogadro constant in Amount of substance, and it separates mole 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
Common Mistake in Mole Calculations
Students often forget to convert volumes from cm³ to dm³ when calculating concentrations, leading to incorrect results.
Always convert volumes to dm³ before using the formula for concentration. For example, if the volume is 250 cm³, convert it to dm³ by dividing by 1000: 250 cm³ = 0.250 dm³. Then use the formula: concentration = mass / volume. If the mass of solute is 5 g, the calculation would be: concentration = 5 g / 0.250 dm³ = 20 g/dm³.
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