So we take our coffee cup calorimeter, we mix the two different types of compounds. We wait a little. We wait for the observed change in temperature to occur, and we have to calculate the change in energy that corresponds to that change in temperature. So our first step is to see exactly what's going on within our coffee cup calorimeter. So we're basically mixing 1 mol of sodium hydroxide and 1 mol of hydrochloric acid. We get dissociated ions, 1 mol of each.