Question

Two moles of oxygen gas is heated at constant pressure from ${25}^{\circ }Cto{75}^{\circ }C$ The increase internal energy of the gas in terms of gas constant $R$ is

• A. $1000$ R
• B. $75$ R
• C. $350$R
• D. $100$ R

Answer 1

Answer: (C)

$350$R

Given,

$f=5$ (for oxygen)

$n=2mole$

$T_1={25}^{0}C=25+273=298K$

$T_2={75}^{0}C=75+273=348K$

The increases in internal energy of the gas at constant pressure,

$dU=(\frac{f}{2}+1)nR(T_2-T_1)$

$dU=(\frac{5}{2}+1)\times 2R\times (348-298)$

$dU=350R$