Pressure

[705714575]

Hi! Could someone please explain how Le Chatelier's principle is effected by changes in pressure?

[Naomi BC]

When we change pressure (by changing the volume, not by using an inert gas), we don't change Ka. Instead, the partial pressures of the gases will have an initial change, then the reaction will occur in a direction based on said change in pressure (as determined by moles of product and reactant in the balanced equation). For example, say we have N2 + 3H2 <-> 2NH3, with initial concentrations of 0.1 mol/L each. If we solve for K, we would find K = 100. Then let's double pressure by halving volume, giving concentrations of 0.2 mol/L each. If we solve for Q now, we will get 25. Therefore, since Q is smaller than K, the reaction will proceed forward, increasing product until the system returns to equilibrium. I hope this makes sense :)

[905934944]

when pressure is increased by changing volume, the concentration of reactants and products change

[Andrew Greenberg 2D]

Le Chateleirs principle shifts a reaction in order to combat stress. If there is an increase in pressure, the reaction will shift toward the side with less moles to relieve the pressure. If there is a decrease in pressure, the reaction will shift towards the side with more moles to combat the change.

[105747606]

hi, increasing pressure, decreases volume, which causes the reaction to shift to the side with fewer moles of gas

[Nicole Li 2B]

It is important to know whether pressure is increased by decreasing volume or by the addition of an inert gas like helium:

1) Pressure increased by decreasing volume:
The reaction will shift to the side with less moles because the concentration of the side with more moles increases more.

2) Pressure increased by the addition of an inert gas:
There will be no change.

I hope this helps!

[Caitlin_Chheda_1K]

Hi! I believe that when pressure is increased (or volume is decreased), the reaction will shift to the side with fewer moles of gaseous or aqueous molecules (solids and liquids are not included in this number). Inversely, if pressure is decreased (or volume is increased), the reaction will shift to the side with greater moles of gaseous or aqueous molecules (solids and liquids are not included in this number).

[Isabel Pon 1D]

Hi!

When pressure increases due to a decrease in volume, the system shifts to the side of the equation with fewer moles of gas. On the other hand, when the pressure of the system decreases and volume increases, the reaction shifts to the side that has more moles of gas.

I hope this was helpful!

[sherwin arian 1K]

Hey! So when pressure is increased it usually means that volume is decreased. When volume decreases the reaction will shift toward the side that has less moles. If the pressure increases but volume stays the same (say by adding a gas that increases the pressure) then there would be no effect on the reaction as volume stays the same.

[Joyce Lee 1K]

An increase in pressure will make it so that the system shifts to the side of the reaction with less moles and vice versa.

[SameeraGurram1]

If pressure increases (perhaps by volume decreasing) in a system, then I like to remember that the reaction equilibrium would move from the side with the greater number of moles to the side with the lower number of moles. And vice versa if pressure decreases (perhaps by volume increasing) in a system, the reaction equilibrium would move from the side with the lower number of moles to the side with a greater number of moles.

[Trinabh Khera Sahni]

Le Chateliers principle basically states that if there is a change in certain conditions (like pressure), the system will respond in a way to reverse or minimize the effects of that change. So if you increase pressure, then the reaction will favor the side (reactants or products) which has a lesser number of moles of gas. If pressure is decreased then the reaction will move to the side which has a greater number of moles.

[106024424]

My TA did a really good example of this in class. It was basically two students who had both hands up and their hands were essentially leaning into each other. The student on the left was the reactants and the student on the right was the products. When the student on the right took away one hand (decrease in pressure/moles of the product) the student on the left would fall forwards. This symbolized a decrease in pressure of a product would cause the reaction to proceed forward to make more product.

[jennacostello8]

With Le Chatelier's Principle, a pressure increase shows that a shift in equilibrium would occur to the side with the least number of moles of gas. Hope this helps.