Question detail
A 250 g sample of water is heated from 20 °C to 80 °C. Calculate the heat energy transferred to the water. (Specific heat capacity of water = 4.18 J/g°C)
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Energetics
Question
A 250 g sample of water is heated from 20 °C to 80 °C. Calculate the heat energy transferred to the water. (Specific heat capacity of water = 4.18 J/g°C)
Answer
The heat energy transferred to the water is 62,700 J. This answer is anchored to Calorimetry and enthalpy measurements.
Explanation
The heat energy transferred to the water is 62,700 J. is the best answer because it directly supports the AQA A-Level Chemistry objective to use q = mcΔT to calculate heat energy transferred. This reasoning is anchored to Calorimetry and enthalpy measurements in Energetics, and it separates calculate 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 Heat Energy Calculation
Students often forget to convert the temperature change (ΔT) into the correct units, leading to inaccurate heat energy calculations.
To fix this, always ensure that the temperature change is in degrees Celsius (°C) when using the formula q = mcΔT. For example, if the initial temperature is 25°C and the final temperature is 75°C, then ΔT = 75 - 25 = 50°C. Substitute this value into the formula along with mass (m) and specific heat capacity (c) to find q accurately.
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