NEET-XII-Chemistry
Previous Year Paper year:2017
- #33A gas is allowed to expand in a well insulated
container against a constant external pressure of
2.5 atm from an initial volume of 2.50 L to a final
volume of 4.50 L. The change in internal energy ΔU
of the gas in joules will be -
(1) +505 J
(2) 1136.25 J
(3) - 500 J
(4) - 505 JdigAnsr: 4Ans : (4)
Sol. ΔU = q + w
Insulated container So, q = 0
ΔU = -PdV
= - 2.5 [4.50 - 2.50]
= - 2.5 × 2 litre - atm = - 5 l atm [1 -atm = 101.3 ≈ 101J]
= - 5 × 101
⇒ - 505 J