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### Change in Pressure

Posted: Sat Jan 19, 2019 11:40 pm
If volume (V) decreases and pressure (P) increases and there are more moles of gas on the left, why does the reaction shift to the right? If there are more moles of gas on the right, why does the reaction shift to the left?

### Re: Change in Pressure

Posted: Sat Jan 19, 2019 11:44 pm
If the volume decreases, then pressure should increase due to Boyle's Law (PV = c). An increase in pressure then means that the reaction wants to return to equilibrium by minimizing this increase. Therefore, it favors the side that has less moles of gaseous molecules. Another way to think about this (if pressure is decreased alongside with volume?) is to calculate the reaction quotient, Q, directly after the change in volume is accounted for in the molar concentrations. If Q < K, then there are too many reactants and not enough products, so the forward reaction will occur to reestablish equilibrium. If Q > K, then there are too many products and too few reactants, so the reverse reaction will occur to produce more reactants.

### Re: Change in Pressure

Posted: Sun Jan 20, 2019 12:30 am
If the volume of a container decreases and pressure increases, a reaction will favor the side of the equation which contains less moles of gas because of the equations goal of reestablishing equilibrium.