Question

1.) In an experiment, a 0.6319 g sample of para-benzoquinone (C₆H₄O₂) is burned completely in a bomb calorimeter. The calorimeter is surrounded by 1.276×10³ g of water. During the combustion the temperature increases from 23.67 to 26.17 °C. The heat capacity of water is 4.184 J g^-1°C^-1.

The heat capacity of the calorimeter was determined in a previous experiment to be 786.6 J/°C.

Assuming that no energy is lost to the surroundings, calculate the molar heat of combustion of para-benzoquinone based on these data.

C₆H₄O₂(s) + 6O₂(g)  2 H₂O(l) + 6 CO₂(g) + Energy

Molar Heat of Combustion = _____ kJ/mol

2.) A bomb calorimeter, or constant volume calorimeter, is a device often used to determine the heat of combustion of fuels and the energy content of foods.

Since the "bomb" itself can absorb energy, a separate experiment is needed to determine the heat capacity of the calorimeter. This is known as calibrating the calorimeter.

In the laboratory a student burns a 1.17-g sample of dimethyl oxalate (C₄H₆O₄) in a bomb calorimeter containing 1040. g of water. The temperature increases from 25.20 °C to 28.40 °C. The heat capacity of water is 4.184 J g^-1°C^-1.

The molar heat of combustion is −1675 kJ per mole of dimethyl oxalate.

• C₄H₆O₄(s) + 7/2 O₂(g) 4 CO₂(g) + 3 H₂O(l) + Energy

Calculate the heat capacity of the calorimeter.

heat capacity of calorimeter = _______J/°C

Answer 1