Reactive metals such as magnesium react readily with acids in aqueous solution. 1.95 g of mg is added to 85.2 ml of a 1.00 m aqueous solution of hcl, producing an increase in temperature of 9.2°c.

Balanced net ionic equation:
Mg(s) + 2H^+(aq) --> Mg^2+(aq) + H2(g)

If the molar heat capacity of 1.00 M HCl is the same as that for water (75.3 J/molC) what is ΔHrxn?