To determine the heat of neutralization, a student mixes 50.0 mL of 1.00 M HCl with 50.0 mL of 1.00 M NaOH in a polystyrene calorimeter. Initial temperature of both solutions = 21.5 C. Maximum temperature after mixing = 28.2 C. Assume density 1.00 g/mL and specific heat 4.18 J/(g*C). Heat capacity of the calorimeter is negligible.
Heat loss to the surroundings during mixing would cause the reported delta H to be:
- Acheck_circle
less negative (less exothermic) than the true value
- B
more negative (more exothermic) than the true value
- C
positive instead of negative
- D
unchanged because heat loss is small
Explanation
Heat loss makes observed delta T smaller, q smaller in magnitude, so |delta H| is underestimated -> reported value is less negative.