Question

A gas contained in a cylinder fitted with
a frictionless piston expands against a
constant external pressure of 1 atm from
a volume of 5 litres to a volume of 10
litres. In doing so it absorbs 400 J of
thermal energy from its surroundings.
Determine the change in internal energy
[Ans: 106.65 J]
of system.​

Answer 1

Answer:

ANSWER

Given data

q=400J

V

1

=5L

V

2

=10L

Δu=q−w (heat is given to the system (+q); work is done by the system (−w)

Δu=q−PdV

=400J−1atm(10−5)L

=400J−5atmL

[∴1Latm=101.33J]

=400J−5×101.33J

=400J−506.65J

=−106.65J