The results show random errors.
The student did not make any measuring errors.
Suggest one reason for the random errors in this experiment.
How to approach this question
Random errors cause unpredictable variation in results. The question states there are no measuring errors (e.g., misreading the thermometer). What other factor in this experiment, which measures temperature change, could vary slightly each time it is performed?
Full Answer
Varying amounts of heat loss to the surroundings between experiments.
Random errors are unpredictable variations in measurements. In this calorimetry experiment, even if the student measures the volumes and masses correctly, other factors can vary slightly between repeats. The most significant is the rate of heat loss to the surroundings. Small variations in air currents in the room, or slight differences in how long the reaction takes, can cause the amount of heat lost to be different in each trial. This would lead to the small variations seen in the recorded highest temperature.
Common mistakes
✗ Citing a measuring error (e.g., "misreading the thermometer"), as the question explicitly rules this out.
✗ Citing a systematic error (e.g., "the thermometer was faulty").
✗ Saying "human error" without being specific.
Expert