The application of Hess's Law frequently presents students with conceptual problems. This series of experiments confirms Hess's Law and offers a robust understanding of this principle. This can be done as a demo completed by the teacher or as a lab with groups of students.
I was at a chemistry teacher workshop recently and we participated in a common Hess’s Law laboratory. Part of the procedure required us to measure about 2 grams of solid NaOH and add it to 100 mL of 0.5 M HCl. We also added 50 mL of 1 M NaOH solution to 50 mL of 0.5 M HCl solution. We then compared the energy change of both containers.