Question

For a gaseous reaction, $A\left(g\right)+3B\left(g\right)\to 3C\left(g\right)+3D\left(g\right)$, $\Delta U$ is $17kcal$ at ${27}^{o}C$. Assuming $R=2cal$ $K^{-1}$ ${mol}^{-1}$, the value of $\Delta H$ for the above reaction is:

• A. $15.8kcal$
• B. $18.2kcal$
• C. $20.0kcal$
• D. $16.4kcal$

Answer 1

The correct option is B $18.2kcal$

$△H=△U+△n_{g}RT△U=17kcal\left(given\right)△n_g=6-4=2△n_{g}RT=2\times 2\times 300=1200Cal=1.2kcal△H=17+1.2=18.2kcal$