What is the enthalpy of this reaction?

Question

A total of 2.00 mol of a compound is allowed to react with water in a foam coffee cup and the reaction produces 132 g of solution. The reaction caused the temperature of the solution to rise from 21.00 to 24.70 ∘C. What is the enthalpy of this reaction? Assume that no heat is lost to the surroundings or to the coffee cup itself and that the specific heat of the solution is the same as that of pure water.

Enter your answer in kilojoules per mole of compound to three significant figures.

Answer 1

The enthalpy of the reaction is equal to the negative of the enthalpy of the solution. The temperature of the solution increases which means that the reaction released heat (exothremic) and the solution absorbed heat.

ΔH_rxn = -q_solution = - m Δ c_p ΔT = -(132g x 4.184 J/gC x (24.70 - 21.00)^oC ) = 2040J

2040J = 2.04 kJ

2.04 kJ/2 mol - 1.02 kJ/mol