In: Chemistry
The equilibrium constant, K, for the following reaction is 1.87×10-2 at 511 K.
PCl5(g) <--------->>>PCl3(g) + Cl2(g)
An equilibrium mixture of the three gases in a
13.1 L container at 511 K
contains 0.209 M PCl5,
6.24×10-2 M
PCl3 and
6.24×10-2 M
Cl2. What will be the concentrations of
the three gases once equilibrium has been reestablished, if the
equilibrium mixture is compressed at constant temperature to a
volume of 7.01 L?
[PCl5] | = | M |
[PCl3] | = | M |
[Cl2] | = | M |
Volume is decreased from 13.1 L to 7.01 L at constant temperature. The concentrations will increase by a factor of
These concentrations will change to restablish the equilibrium. To determine concentrations at new equilibrium, an ICE table is prepared.
Initial concentration (M) | 0.391 | 0.117 | 0.117 |
Change in concentration (M) | -x | x | x |
Equilibrium concentration (M) | 0.391-x | 0.117+x | 0.117+x |
The equilibrium constant
This is quadratic equation with solution
or
The value -0.224 is discarded as it will lead to negative value for chlorine concentration.
These are the equilibrium concentrations.