Question

For the reaction, at constant temperature, $\Delta H-\Delta U$ is :
$C_3{H}_8$(g) + ${5O}_2$(g) $⟶$ ${3CO}_2$(g) + ${4H}_{2}O\left(\ell \right)$

• A. $-3RT$
• B. $3RT$
• C. $RT$
• D. None of these

Answer 1

Answer: (A)

$-3RT$

For the reaction,

$C_3{H}_8$(g) + ${5O}_2$(g) $⟶$ ${3CO}_2$(g) + ${4H}_{2}O\left(\ell \right)$

$\Delta n=3-(1+5)=-3$

At constant temperature, $\Delta H-\Delta U$ $=\Delta nRT=-3RT$