The chemical reaction shown below is carried out in a coffee cup calorimeter. A student mixes 10.0 mL of 0.100 M H2A(aq) and 20 ml of 0.100 M NaOH(aq), both initially at 25'C. The student records the highest temperature of 40'C for the reaction H2A (aq) + 2 NaOH(aq) → Na2A (aq) + 2 H20() AH - ??? kJ/mol
a. What indicates that this is an acid-base reaction? Explain your answer.