question_answer 1)

  At 500 K, equilibrium constant, \[{{K}_{c}}\], for the following reaction is 5: \[\frac{1}{2}{{H}_{2}}(g)+\frac{1}{2}{{I}_{2}}(g)\underset{{}}{\leftrightarrows}HI(g)\] What would be the equilibrium constant \[{{K}_{c}}\]for the reaction? \[2HI(g)\underset{{}}{\leftrightarrows}{{H}_{2}}(g)+{{I}_{2}}(g)\] (a) 0.04                                 (b) 0.4                                   (c) 25                     (d) 2.5

Answer:

  (a) \[\frac{1}{2}{{H}_{2}}(g)+\frac{1}{2}{{I}_{2}}(g)\underset{{}}{\leftrightarrows}HI(g)\] \[{{K}_{c}}=\frac{[HI]}{{{[{{H}_{2}}]}^{1/2}}{{[{{I}_{2}}]}^{1/2}}}=5\] For the reaction   \[2HI(g)\underset{{}}{\leftrightarrows}{{H}_{2}}(g)+{{I}_{2}}(g)\]                                 \[{{K}_{c}}=\frac{[{{H}_{2}}][{{I}_{2}}]}{{{[HI]}^{2}}}=\left( \frac{1}{{{K}_{c}}} \right)=\frac{1}{25}\] = 0.04