Question detail
If 50 g of water absorbs 2100 J of heat energy, what is the change in temperature if the specific heat capacity of water is 4.18 J/g°C?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
AS practical skills and required practical activities
Question
- A. 10°C
- B. 5°C
- C. 1°C
- D. 50°C
Answer
10°C
Explanation
The correct option is 10°C. 10°C is the best answer because it directly supports the AQA A-Level Chemistry objective to required practical 2: measure an enthalpy change. This reasoning is anchored to AS required practical activities in AS practical skills 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
Incorrect Measurement of Enthalpy Change
Students often forget to account for the specific heat capacity of the solution when calculating the enthalpy change, leading to inaccurate results.
To fix this, remember to use the formula q = mcΔT, where q is the heat energy, m is the mass of the solution, c is the specific heat capacity, and ΔT is the change in temperature. Substitute the values correctly and ensure to include units in your final answer. For example, if you have 100 g of water (m = 100 g), with a specific heat capacity of 4.18 J/g°C (c), and a temperature change of 10°C (ΔT), the calculation would be: q = 100 g × 4.18 J/g°C × 10°C = 4180 J. Thus, the enthalpy change is 4180 J.
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