calorometer constant

Question

Assume you produce 2 moles of water in the neutralization reaction of HCl and NaOH with a temperature increase of 5 degrees. What is your calorimeter constant?

Answer 1

2HCl + 2NaOH ==> 2H2O + 2NaCl

The calorimeter constant is the amount of heat absorbed (q) / change in temperature (∆T).

We are given ∆T as 5º, so we need to first find the amount of heat absorbed by the water. For a neutralization reaction between a strong acid (HCl) and a strong base (NaOH), this value is given as approximately -57.1 kJ/mole. Thus...

q = (2 mols)(-57.1 kJ/mol) = -114.2 kJ of heat absorbed

Calorimeter constant (C) = q / ∆T = -114.2 kJ / 5º

C = 22.8 kJ/º

(note: if you use a slightly different value for the ∆H_{neutralization}, you will obviously get a slightly different answer).