A 0.1375 g sample of solid magnesium is burned in

aconstant-volume bomb calorimeter that has a heat capacity of3024

J / oC. The temperature increases by 1.126oC.

Calculate the heat given off by burning Mg, inkJ/g and in

kJ/mol.

24.76 kJ/g

844.8 kJ/mol

Explanation:

The heat produced by the burning of the solid magnesium is equal to the heat absorbed by the calorimeter, which causes its temperature to increase.

First, we calculate the heat absorbed by the calorimeter, where C is the heat capacity and Δt is the temperature change.

Q = CΔt = (3024 J·°C⁻¹) (1.126 °C) = 3405 J

This is the same amount of heat that was produced by burning the magnesium

Now we can calculate the heat produced per gram of magnesium:

(3405 J) (1 kJ/1000 J) / (0.1375 g) = 24.76 kJ/g

We can convert grams to moles using the atomic weight of Mg (24.305 g/mol).

(24.76 kJ/g) (24.305 g/mol) = 844.8 kJ/mol