Question

One mole of an ideal monoatomic gas expanded irreversibly in two-stage expansion.
State 1 ($8.0$ bar, $4.0$ litre, $300K$)
State 2 ($2.0$ bar, $16$ litre, $300K$)
State 3 ($1.0$ bar, $32$ litre, $300K$)
Total heat absorbed by the gas in the process is:

• A. $116J$
• B. $40J$
• C. $4000J$
• D. None of these

Answer 1

The correct option is C $4000J$

We know that, W = -P (ext.) [V₂ - V₁]

From stage 1 to stage 2;

W₁ = -2 [16 - 4] x 100 = -2400 J

Now, from stage 2 to stage 3;

W₂ = - 1 [32 - 16] x 100 = -1600 J

W = W₁ + W₂ = [ -2400 -1600 ] = -4000 J

Since, heat absorbed, q = -W

∴ q = 4000 J