Pressure effect on a system

[Kassandra Javier 2D]

How do you know when adding pressure to a system will affect or not affect a system? Does pressure only affect the reaction if it is applied to only one species in the reaction instead of the entire system?

[Vanessa Wiratmo 3k]

Hello,

When looking at the effect of pressure on an equilibrium reaction, it is important to notice whether or not the pressure is changing the concentration of the reactants and products. For example, if you have your reaction in a 1.00L vessel and you increase pressure by changing the volume to 0.5L, the concentration of the gasses are increasing. This is because concentration is mol/L. If the volume of the container decreased by half, the concentration increases x2. Because of this change in concentration, the Q value will shift. If Q>K, then the reaction will shift left. If Q<K, then the reaction will shift right.

Another way pressure can change in a reaction is by adding an inert gas to the system. The gas added is one that is non reactive such as H2. The addition of the gas increases pressure, but it does not change the concentration of the reactants or products. There was no change in volume. The reaction stays at equilibrium.

[605721741]

Pressure change will affect a system if the change in pressure is achieved through a change in volume because changes in volume affect molar concentration.

[Barbara Soliman 1G]

Adding pressure to a system will only affect it when one side of the reaction has more moles than the other. If each side has the same amount of moles, then adding pressure will not affect it. Also, if you add an inert gas, it does not affect the reaction as it is unreactive. If you add pressure to one side of the reaction, it will affect the entire system. Hope this helps!

[Michael Vigman 2D]

It is important to note whether pressure change is being affected via a change in volume. In which case, volume and pressure can be thought of inversely.

Increasing pressure will shift the rxn towards the side of the rxn with fewer moles.
Decreasing pressure will shift the rxn towards the side of the rxn with more moles of gas.

[Rose Arcallana 2B]

If changing the pressure by changing the volume of the reaction, then it will affect the system. On the other hand, if the pressure is altered by an inert gas, this will not affect the system as they don't react with the system. hope it helps! :)

[riddhiparikh]

When there is an increase in pressure, the equilibrium will shift towards the side of the reaction with fewer moles of gas. When there is a decrease in pressure, the equilibrium will shift towards the side of the reaction with more moles of gas. This is what I found when I looked into this question. So overall, pressure can affect the system.