What is the stoichiometry formula, and answer to this question?

Question

When 50mL of aqeous HCl was mixed with 50mL of NaOH (in excess), the temperature of the solution increased from 25C to 32.41C. The reaction is...
NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(aq).
change in heat= -57.3kJ
What is the molarity of the original HCl solution?
Assume the heat capacity of the solution is the same as pure water (4.184J/g*C), the density of the solution is 1g/mL, and there is no loss of heat to the surroundings

Answer 1

The heat released from the reaction is the heat absorbed by water:
(50+50)*4.184*(32.41-25) = 3.10kJ
I believe the data you give "change in heat= -57.3kJ" is actually for one mole: "change in heat= -57.3kJ/mol"
Since: (3.10kJ) / (57.3kJ/mol) = 0.0541 mol is the amount of chemical in the original 50mL, so the molarity of the original HCl solution is: 0.0541/50mL = 1.08M