Navigate back to the activity.

Temperature Change of Dissolving Salt: Instructor's Guide

Main Ideas

  • First and second law of thermodynamics
  • Enthalpy of dissolution
  • Specific heat
  • Heat transfer

Students' Task

Estimated Time: 40-60 minutes

Students are broken into small groups and asked to calculate the energy released and the change in temperature of a cup of water due to the dissolution of salt.

Prerequisite Knowledge

  • Familiarity with the first law of thermodynamics is useful.
  • Experience in calculating heat transfer due to thermodynamic processes is useful.


Activity: Introduction

No introduction is needed for this activity. Students can be placed in small groups and then let to work on the handout.

Activity: Student Conversations

While there are no students at the school who have done this lab, it seems like an interesting lab. I do believe that it would be a difficult lab to do, given students' previous inability to accurately mass water. I'm not sure if this would be a good idea to fully do a lab on, but I think it could be interesting to do in a class as a demonstration of the temperature change. -Amanda Abbott

Activity: Wrap-up

Discuss the answers to the questions on the worksheet with the entire class. Ask in particular if students can think of a way to measure the change in entropy for the process experimentally.

Also ask about any assumptions made in the problem. In particular, this problem neglects the heat capacity of the salt itself, as well as how the heat capacity of the water would change as the salt dissolves into the water.


Personal Tools