With hydrochloric acid you might get something like this

Heats of reaction.

Use a calorimeter for which you have already established a calorimeter constant.

The heat absorbed in raising the calorimeter is exactly equal to the heat lost by the reaction.

1. Calculate the heat absorbed by calorimeter.

   ΔH = Calorimeter constant X ΔT_{calorimeter warming}

2. Set this ΔH for the reaction.

3. Standardize by dividing ΔH by the number of moles of metal reacted. This gives us the number of joules/mole.

4. Here's the interesting part: Now that you have experimented with several acid and metal combination, which determines the ΔH, the acid used, or the metal used? Why might this be???. Since you have balanced equations for each trial, convert those reactions into net ionic equations (leave out any species that does not change from left to right across the reaction arrow. Here's one for an example. 

Zn + 2 HCl --> ZnCl₂ + H₂

Zn + 2 HCl --> ZnCl₂ + H₂         Cl^1- on both sides so cross out