For the gas phase reaction, 2 H CN ⇌ H 2 + ( CN ) 2 ; K p = 4 × 1 0 − 6 at 500 ℃. If the equilibrium partial pressures of H 2 ( g ) and ( CN ) 2 ( g ) are equal to 0.5 a t m each, the initia

Question

For the gas phase reaction, 2 H CN ⇌ H 2 ​ + ( CN ) 2 ​ ; K p ​ = 4 × 1 0 − 6 at 500 ℃. If the equilibrium partial pressures of H 2 ​ ( g ) and ( CN ) 2 ​ ( g ) are equal to 0.5 a t m each, the initial pressure of H CN ( g ) in atm is:

TestHub · Accepted Answer

Let the initial pressure of HCN in the following reaction be $P_{0}$ atm.

$2 H CN (g) ⇌ H_{2} (g) + (CN)_{2} (g)$

Initial pressure: $P_{0}$

Pressure at equilibrium: $P_{0} - x$ $x /2$ $x /2$

Given that $x /2 = 0.5$ ⟹ $x = 1$ .

$K_{p} = \frac{P ( H _{2} ) P (( CN ) _{2} )}{P ( H CN ) ^{2}} = \frac{( 0.5 ) ( 0.5 )}{( P _{0} - 1 ) ^{2}} = 4 \times 1 0^{- 6}$

On solving, $P_{0} = 251$ atm.

Chemistry - Chemical Equilibrium Question with Solution | TestHub

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