Q82 / 200 · NEET 2010 (Screening) · Chemistry

In which of the following equilibrium $\mathrm{K}_C$ and $\mathrm{K}_{\mathrm{P}}$ are not equal ?

  • A
    $2 \mathrm{NO}(\mathrm{g}) \rightleftharpoons \mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g})$
  • B
    $\mathrm{SO}_2(\mathrm{~g})+\mathrm{NO}_2(\mathrm{~g}) \rightleftharpoons \mathrm{SO}_3(\mathrm{~g})+\mathrm{NO}(\mathrm{g})$
  • C
    $\mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{g})$
  • Correct answer
    D
    $2 \mathrm{C}(\mathrm{s})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{CO}_2(\mathrm{~g})$

Solution

Key Idea The reaction for which the number of moles of gaseous products $\left(n_{\mathrm{p}}\right.$ ) is not equal to the number of moles of gaseous reactants $\left(\mathbf{n}_{\mathrm{R}}\right)$, has different value of $\mathrm{K}_{\mathrm{c}}$ and $\mathrm{K}_{\mathrm{p}}$. (a) $\boldsymbol{n}_{\mathrm{P}}=\mathbf{n}_{\mathrm{R}}=2$, thus, $\mathrm{K}_{\mathrm{p}}=\mathrm{K}_{\mathrm{c}}$ (b) $\mathrm{n}_{\mathrm{P}}=\mathrm{n}_{\mathrm{R}}=2$, thus, $K_{\mathrm{p}}=\mathrm{K}_{\mathrm{c}}$ (c) $\mathrm{n}_{\mathrm{P}}=\mathrm{n}_{\mathrm{R}}=2$, thus, $\mathrm{K}_{\mathrm{p}}=\mathrm{K}_{\mathrm{c}}$ (d) $n_p=2, n_R=1$, thus, $K_p \neq K_c$

Hence, the correct answer is option: 'D'.

Relevant Questions