Question

A sturdy, sealed container contains 0.2 moles of helium gas. It is initially sitting in a room at 20 °C, and the pressure of the gas is observed to be 200 kPa. The container is then placed in boiling water.

(a) What will the pressure be when the temperature of the gas reaches equilibrium?

(b) What is the change in entropy of the gas during this process?

(c) Is work done on or by the gas? If so, how much?

(d) It heat transferred to or from the gas? If so, how much?

Answer 1

given :

T1 = initial temperature = 20 oC = 293 K

P1 = initial pressure = 200 kPa = 200,000 Pa

n = 0.2 moles

the gas is monoatomic.

a) final temperature = T2 = 100 oC = 373 K

final pressure = P2 = ?

The volume is constant, so we can write :

b) As the process is constant volume process or isochoric process,

the exhange of heat is expressed as

The change in entropy =

[answer]

c) As the process is isochoric, work done is zero. [answer]

d) As the temperature of the gas increases, the internal energy increases, and the work done is zero in isochoric process.

then from First Law of Thermodynamics : , as change in internal energy is +ve, Heat exchange is also positive and so Heat is transfered to the gas. [answer]