Question

For the reaction, $C_2{H}_{5}OH\left(\ell \right)+3O_2\left(g\right)\to 2C{O}_2\left(g\right)+3H_{2}O\left(\ell \right)$ which one is true?

• A. $△H=△E-RT$
• B. $△H=△E+RT$
• C. $△H=△E+2RT$
• D. $△H=△E-2RT$

Answer 1

The correct option is A $△H=△E-RT$

$C_2{H}_{5}OH\left(l\right)+3O_2\left(g\right)⟶2C{O}_2\left(g\right)+3H_{2}O\left(l\right)$

We know,

$△H=△E+△n_{g}RT$

$△n_g=$ No. of gaseous moles of product $-$ No. of gaseous moles of reactant.

$\Rightarrow \Delta n_g=2-3=-1$

Therefore, $△H=△E-RT$.