In the previous section we saw that the concentrations of the substances are raised to the?power of the coefficients?from the balanced equation

This means the?K_c?expression?is dependent on a specific equation

For example, take the reaction between nitrogen and hydrogen to make ammonia

?N_2(g)??? +??? 1?H_2(g)? ?? ? ?NH_3(g)

The?K_c?expression for this reaction is:

If you double the stoichiometry the equation becomes

N_2(g)??? +??? 3H_2(g)? ? 2NH_3(g)

The new?K_c?expression for this reaction is then:

What is the relationship between these two?K_c?values? You can probably see that when we double the coefficient the new?K_c is the square of the original value:

If we reverse the equation:

2NH_3(g)?? N_2(g)??? +??? 3H_2(g)

K_c? becomes the reciprocal of the original K_c?value:

Test your understanding in the following example:

Answer:

The correct option is?B.

The original equation has been reversed and halved, so the?K_c?value must be square rooted and inverted to obtain the reciprocal