doubling pressure

[Ruiting Jia 4D]

When talking about Le Chatelier's implications on changing physicial parameters, such as pressure, why did Dr. Lavelle double pressure to find the new initial concentration of the equation : N2 + 3 H2 <=> 2 NH3 ??

[AngelaZ 1J]

Lavelle was giving an example of how a reaction responds to minimize the effect of increasing pressure (by decreasing volume). If P doubled (V halved), then there would be new initial concentrations (since concentration=moles/volume). Q would then be solved for these new concentrations so that we could compare Q to K and see which way the reaction would shift. In this case, Q<K so the reaction would shift to the right.

[deepto_mizan1H]

In addition to the reply above, it is a strong example of how the principle works to rebalance the system (pushing the equilibrium to either direction).