Hydrogen chloride gas, 0.100 mol, was dissolved into water to make 125 g of solution.

If the final temperature of water was 32.3 C, what was the initial temperature? Assume the specific heat capacity of the solution is the same as that of water, 4.18 J·g1·C1, and that the solution is thermally isolated (no heat enters or leaves the solution from the environment).

HCl(g) ---> H+(aq) + Cl-(aq) deltaH = -74.9 kJ/mol
can you please explain the problem thanks

Use q=specific heat capacity × mass × delta T
q= -74.9 kJ/mol convert that to J/mol and you get -74900 J/mol
Fill in the rest of the formula -74900J/mol = 4.18J(g*c) * 125g*(32.3- Initial Temperature)
solve for initial temperature and you will get 175.64, You divide this by .100 mol and will get a temperature of 17.56 C or rounded 18 C