Question

A 0.2475−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 2.027°C. (a) Calculate the heat associated with the burning Mg in kJ/g. kJ/g (b) Calculate the heat associated with the burning of Mg in kJ/mol.

Answer 1

ΔH = -601.9 kJ/ mol Mg

Step-by-step explanation:

Step 1: Data given

Mass of the solid magnesium sample = 0.2475 grams

The heat capacity of calorimeter = 3024 J/°C

The temperature increases by 2.027 °C

Step 2: Calculate the heat transfer

q = Ccal * ΔT

⇒with q = the heat transfer

⇒with Ccal = the heat capacity of calorimete 3024 J/°C

⇒ΔT = The temperature increases by 2.027 °C

q = 3024 J/°C * 2.027 °C

q = 6129.6 J

Since this is an exothermic reaction, ΔH will be negative

Step 3:Calculate the heat associated with the burning of Mg

Heat = -6129.6 J / 0.2475 grams Mg

Heat = 24766 J/grams = -24.77 kJ /grams Mg

Heat = -24.77 kJ/ grams * 24.3 g/mol

ΔH = -601.9 kJ/ mol Mg