Question

a)
5) 1 mole of an ideal gas is kept in a cylinder with a movable frictionless and
massless piston at pressure of 1.0mPa, and temperature 27°C. It is then expanded til
its volume is doubled. How much work is done if the expansion is isobaric?
a) 49 kJ
b) 4.9 kJ
c) 490 kJ
d) 0.49 k​

Answer 1

Correct Question :

2 mole of an ideal gas is kept in a cylinder with a movable frictionless and massless piston at pressure of 1.0mPa, and temperature 27°C$.$ It is then expanded til

its volume is doubled. How much work is done if the expansion is isobaric ?

Answer :

★ Work done in isobaric process is given by

• W = P ∆V

W denotes work done

P denotes pressure

∆V denotes change in volume

★ Ideal gas equation :

• PV = nRT

Temperature = 27°C = 300K

➝ 10‾³ × V = 2 × 8.314 × 300

➝ V = 4988.4 × 10³ m³ ..... (i)

Now work done in expansion ;

➝ W = P (V₂ - V₁)

ATQ : V₂ = 2V

➝ W = P (2V - V)

➝ W = P × V

From equation (i)

➝ W = 10‾³ × (4988.4 × 10³)

➝ W = 4.9 kJ

∴ (B) is the correct answer!

★ Additional Information :

• The thermodynamic state of a system is characterized by its internal energy, not heat. That is internal energy is a state variable.
• For this reason, the statement like a gas in given state has a certain amount of energy is meaningful.

Answer 2

its volume is doubled. How much work is done if the expansion is isobaric ?

➝ W = P (V₂ - V₁)

ATQ : V₂ = 2 V

➝ W = P (2 V - V)

➝ W = P × V

From equation (i)

➝ W = 10‾³ × (4988.4 × 10³)

➝ W = 4.9 k J

∴ (B) is the correct answer!