There are fewer moles on the right hand side of the equation for the Haber process: \(\begin{array}{rcl} N_{2}(g) + 3H_{2}(g) & \rightleftharpoons & 2NH_{3}(g) \\ 1 ...
It is more obvious in reactions that do not go to completion that the reaction is reversible. This is the case when the reaction mixture contains both reactants and products.