Question

Toluene, C7H8, is used in the manufacture of explosives such as TNT (trinitrotoluene). A 1.500 g sample of liquid toluene was placed in a bomb calorimeter along with excess oxygen. When the combustion of the toluene was initiated, the temperature of the calorimeter rose from 25.000 °C to 26.413 °C. The products of the combustion are CO2(g) and H2O(l), and the heat capacity of the calorimeter was 45.06 kJ °C-1. Write the balanced chemical equation for the reaction in the calorimeter. How many joules were liberated by the reaction? How many joules would be liberated under similar conditions if 1.000 mol of toluene was burned?

Answer 1

Answer:

There were 63.67 kJ liberated

If 1 mol of toluene was burned, there would be liberated 3906 kJ / mole

Explanation:

Step 1: Data given

Mass of the toluene sample = 1.500 grams

The temperature of the calorimeter rose from 25.000 °C to 26.413 °C

Write the balanced chemical equation for the reaction in the calorimeter.

C7H8(l)  +  9O2(g) ⇒  7CO2(g) + 4H2O(l)

Step 2: Calculate Q of the calorimeter

Q = C * Δt

Q = 45.06 kJ/ °C * ( 26.413 - 25)

Q = 63.67 kJ

Step 3: Calculate moles of toluene

Moles toluene = mass toluene / molar mass toluene

Moles toluene = 1.500 grams /92.14 g/mol

Moles toluene = 0.0163 moles

Step 4:  Calculate energy per mole

energy per mole = 63.67 kJ / 0.0163 moles = 3906 kJ / mole