A 0.167 g sample of Mg(s) is burned in a bomb calorimeter which has a heat capacity of 3081 J/°C. In this process, the temperature of the calorimeter increased by 1.34 °C. Calculate the heat given off by burning Mg(s) under these conditions (in kJ/mol).
3081 J/C x 1.34 C = J heat released by burning 0.167 g Mg.
Convert that to J/24.32 (1 mol) Mg.
To calculate the heat given off by burning Mg(s), we can use the equation:
q = C * ΔT
Where:
q is the heat given off
C is the heat capacity of the calorimeter
ΔT is the change in temperature
First, let's convert the mass of Mg(s) from grams to moles. The molar mass of Mg is 24.31 g/mol.
moles of Mg = mass of Mg / molar mass of Mg
moles of Mg = 0.167 g / 24.31 g/mol
moles of Mg ≈ 0.00688 mol
Now, we can calculate the heat given off by burning Mg(s).
q = C * ΔT
q = 3081 J/°C * 1.34 °C
q ≈ 4127 J
Since we want the answer in kJ/mol, we need to convert the heat from joules to kilojoules and divide it by the moles of Mg burned.
heat given off = q / moles of Mg
heat given off = 4127 J / 0.00688 mol
heat given off ≈ 599.6 kJ/mol
Therefore, the heat given off by burning Mg(s) under these conditions is approximately 599.6 kJ/mol.