Question

the internal energy of a gas decreases by 1.65kj when it transfers 1.87kj of energy in the form of heat to the surroundings.(a)calculate the work done by the gas on the surroundings.(b)does the volume of gas increase or decrease?

Answer 1

Answer Sheet:

a) The internal energy of the system decreases means the internal energy is negative which indicate the work done by the system.

According to 1st law of thermodynamics U = q - w -------------(1)

where, U = internal energy, q= heat energy, w= work

( work done by the system i.e negative work)

Given, internal energy= - 1.65 kJ

heat energy= 1.87 kJ

Putting these values in the equation (1 ) we have

- 1.65 kj = 1.87kj - w

Or, w = 3.52 kj

So work done by the system = 3.52kj

b) The work done by the system so the volume of the system is increases.