Energy changes
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The enthalpy change of the reaction between HCl and NaOH was found by mixing them in a plastic cup. In the first experiment, 10 cm3 of each solution was used, and the temperature change was noted. In the second experiment 50 cm3 of each solution was used and the temperature change was noted. In both experiments, the concentration of each solution was 1.0M. Which of the two experiments is likely to lead to the more accurate determination of a temperature change? I think the answer is the second one because the temperature rise in both experiments will be the same, but the volume of the overall mixture is larger in the second experiment so there will be less heat loss since the surface area:volume ratio is smaller. Am I right?
Basically you have the right idea. In theory the temperature change should the same. However in practice there will be a difference, and you have correctly identified the probable cause.
Ulex
Risk assessment
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updated: 11 November 2003
