When a 6.00 g sample of KBr is dissolved in water in a calorimeter that has a total heat capacity of 2.71 kJ ⋅ K - 1, the temperature decreases by 0.370 K. Calculate the molar heat of solution of KBr.

Molar heat enthalpy of KBr = - 19.89 kJ/mol

Explanation:

Change in temperature (Δt) = 0.370 K

Heat capacity = 2.71 kJ ⋅ K^-1

Heat absorbed by calorimeter = heat capacity * change in temperature

= 2.71 * 0.370

= 1.0027 kJ

Molar mass of KBr = 119 g/mol

No. of moles of KBr = 6.00/119

= 0.0504 mol

Heat absorbed by the calorimeter is given by KBr.

Now calculate the heat released by per mol of KBr as follows:

Heat released by per mol of KBr = 1.0027 kJ / 0.0504 mol

=19.89 kJ/mol

Heat is released therefore, sign will be negative.

Molar heat enthalpy of KBr = - 19.89 kJ/mol