Question

A 0.2175−g sample of solid magnesium is burned in a constant-volume bomb calorimeter that has a heat capacity of 3024 J/°C. The temperature increases by 1.782°C.

Calculate the heat given off by the burning Mg in kJ/g.
Calculate the heat given off by the burning Mg in kJ/mol.

Answer 1

Answer: 5.27 kJ/g and 589.6 kJ/mol.

Explanation: heat given off = mass x specific heat capacity x change in temperature The specific heat capacity of Mg is 1.020 J/ g oC

. The molar mass of Mg is 24.31 g/mol 1. Therefore, the number of moles of Mg in the sample is:0.2175 g / 24.31 g/mol = 0.00894 molNow, we can calculate the heat given off by the burning Mg in kJ/mol by dividing the heat given off by the number of moles of Mg:5.27 kJ/g / 0.00894 mol = 589.6 kJ/mol 1.