A 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 Δ U of the gas in joules will be

Question

A 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 Δ U of the gas in joules will be (A) -500J (B) -505J (C) +505J (D) 1136.25J

Tardigrade Admin · Accepted Answer

Δ U = q + w For adiabatic process, q=0 ∴ Δ U = w =- P ⋅ Δ V =-2.5 atm ×(4.5-2.5) L =-2.5 × 2 L - atm =-5 × 101.3 J =-506.5 J ≈-505 J

Q. A gas is allowed to expand in a well insulated container against a constant external pressure of $2.5 a t m$ from an initial volume of $2.50 L$ to a final volume of $4.50 L$ . The change in internal energy $Δ U$ of the gas in joules will be

-500J

-505J

+505J

1136.25J

$Δ U = q + w$
For adiabatic process, $q = 0$
$∴ Δ U = w$
$= - P \cdot Δ V$
$= - 2.5 a t m \times (4.5 - 2.5) L$
$= - 2.5 \times 2 L - a t m$
$= - 5 \times 101.3 J$
$= - 506.5 J$
$\approx - 505 J$

Q. A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5atm from an initial volume of 2.50L to a final volume of 4.50L. The change in internal energy ΔU of the gas in joules will be