Textbook Problem 4A.13

[Titania Le [2F]]

"A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution in the calorimeter, resulting in a temperature rise of 7.32°C. In a subsequent experiment, 100.0 mL of 0.200 M HBr(aq) and 100.0 mL of 0.200 M KOH(aq) were mixed in the same calorimeter and the temperature rose by 2.49°C. What is the change in the internal energy of the reaction mixture as a result of the neutralization reaction?"

Hello! I'm confused as to why the mass of the 0.200 L solution isn't factored in when calculating the change of U for the reaction mixture.

[Alicia Li 2E]

Hi! I think the volume isn't factored in because the first part of the problem allows us to find the kJ/C of the calorimeter. To my understanding, the value should be constant for the calorimeter, regardless of what reaction takes place inside the calorimeter.