Temperature change? Check my answer please.

Question

Predict how the temperature change that you measure for 25 mL of 1 M NaOH added to 25 mL of 1 M hydrochloric acid compare to the temperature change when 50 mL of 1 M NaOH is added to 50 mL of 1 M hydrochloric acid.

a

The measured temperature change will be the same

b

​The measured temperature will be higher because the mass of the solution is lower

c

​The measured temperature will be lower because fewer mols of the acid and base react

d

Cannot predict

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I believe the answer is B: ​The measured temperature will be higher because the mass of the solution is lower

Is this right??

Answer 1

Hello, Abigail,

I might predict that the temperature change would remain the same. In both experiments, the heat released will be the same per ml of final solution. Since the twice the energy has to heat twice the mass, the temperature would be the same. Think of the 50 ml case as two separate 25 ml experiments.

Bob

Answer 2

As the actual amount of acid and base is doubled in the second case, the reaction heat is expected to double. But the amount of solution to be heated is doubled also ( 100 mL vs. 50 mL). So, twice the amount of heat and twice the amount of solution to be heated would mean the temperature change in each case would be the same. The answer should be a.