For the equilibrium
`N_(2)+3H_(2) hArr 2NH_(3)` at 298K
and 5 atm. Pressure, increasing pressure to 50 atm, will ( here K is the equilibrium constant )

Options

A. decrease the yield of `NH_(3)` as well as the value of K
B. increase the yield of `NH_(3)` as well as the value of K
C. increase the yield of `NH_(3)`, but will not change the value of K
D. increase the yield of `NH_(3)` , but will decrease the value of K

Answer

C

Explanation

Equilibrium constant, K depends only upon temperature. Increasing pressure will increase the yield of `NH_(3)` by shifting the equilibrium in the forward direction but will not affect the value of K. It is clear from the following explanation. Let equilibrium concentration of reactants and products are
`[NH_(3)]=.^(n)NH_(2)//V,[N_(2)]=nN_(2)//V`
`[H_(2)]=nH_(2)//V`
where V is the volume of the container.
`K=([NH_(3)]^(2))/([N_(2)][H_(2)]^(3))=([nNH_(3)//V]^(2))/([nN_(2)//V][nH_(2)//V]^(3))`
`=((nNH_(3))^(2)V^(2))/((nN_(2))(nH_(2)))`
Increasing pressure increases `.^(n)NH_(3)` but also decrases V. This explains as to why K does not change with change in pressure.