## Partial Pressure

$PV=nRT$

Philip
Posts: 100
Joined: Sat Sep 07, 2019 12:16 am

### Partial Pressure

2NO + O2 = 2NO2

Why would decreasing the volume of a system increase the partial pressure of NO2?

romina_4C
Posts: 100
Joined: Thu Jul 11, 2019 12:17 am

### Re: Partial Pressure

On the left side of the equation (reactant side) we have 3 moles of reactants and on the right side of the equation (product side) we have two moles of products. Decreasing the volume of a system increases the pressure of the system, and thus the reaction wants to shift to the side with fewer moles of gas to decrease the pressure. Thus, since the right side (product side) has fewer moles of gas (2<3), the reaction will shift to the right to form more products, thus more NO2 will be formed, increasing its partial pressure.

WGaines_2E
Posts: 47
Joined: Mon Nov 18, 2019 12:18 am

### Re: Partial Pressure

Decreasing the volume of a system is going to cause the pressure to rise. To negate the increase in pressure, the reaction is going to proceed in the direction which favors the least moles of gas. Since there is two moles of gas as products and 3 moles gas as reactants, the reaction is going to proceed in the forward direction as volume is decreased.

kim 2I
Posts: 105
Joined: Thu Jul 25, 2019 12:17 am

### Re: Partial Pressure

When you decrease the volume of the system, the overall pressure is increased. Therefore, the reaction shifts towards the side with less moles of gas and for this reaction, it would be towards the products (2 moles vs the 3 moles in the reactants).

Amanda Mei 1B
Posts: 109
Joined: Sat Aug 24, 2019 12:16 am

### Re: Partial Pressure

Remember that decreasing the volume of a system causes pressure to increase, since the same number of moles in a smaller space will collide more frequently. If you the pressure of the whole system increases due to a decrease in volume, the system will want to negate that change and restore equilibrium. Thus, it will shift to the side with fewer moles, since that gives a lower pressure (fewer moles in the same space means fewer collisions). The forward reaction (right side) would be favored since there are 2 moles of gas compared to 3.

Sally Qiu 2E
Posts: 105
Joined: Fri Aug 30, 2019 12:18 am

### Re: Partial Pressure

when you decrease the volume of a reaction, you also increase the pressure. thus the reaction will shift towards the side that has fewer moles of gas.

Jacob Motawakel
Posts: 103
Joined: Wed Sep 18, 2019 12:20 am
Been upvoted: 1 time

### Re: Partial Pressure

because there are less moles on the right side, so as volume decreases, the side with less moles will increase.

Nawal Dandachi 1G
Posts: 102
Joined: Sat Sep 28, 2019 12:16 am

### Re: Partial Pressure

When you decrease the volume, you're increasing the pressure. Therefore, the reaction would favor the side with less moles, which is the products side. And because the reaction shifts forward, the partial pressure of NO2 will increase.

Leonardo Le Merle 1D
Posts: 56
Joined: Wed Feb 27, 2019 12:16 am

### Re: Partial Pressure

This is a feature of Le Chatelier's Principle; I think it should be in Week 3 notes if that helps!

Tanmay Singhal 1H
Posts: 143
Joined: Sat Jul 20, 2019 12:16 am

### Re: Partial Pressure

yes because of le chatelier's principle

Frank He 4G
Posts: 50
Joined: Tue Nov 12, 2019 12:19 am

### Re: Partial Pressure

Yeah, Chatelier's principle would explain this. Generally, the less particles floating around, the less energy has to be used to compress the system, so the side with the least moles would be favored.

Posts: 45
Joined: Sat Aug 17, 2019 12:16 am

### Re: Partial Pressure

According to Le Chatelier's principle if there are more moles on the right side then the reaction shifts right creating more products.

Alan Cornejo 1a
Posts: 98
Joined: Fri Aug 30, 2019 12:15 am

### Re: Partial Pressure

When decreasing the volume of a reaction, you also increase the pressure. Using le chatliers principle we find the reaction will shift towards the side that has fewer moles of gas, which in this reaction is the products as there are only 2 mols of gas compared to three on the reactants side.

Gurmukhi Bevli 4G
Posts: 49
Joined: Wed Nov 14, 2018 12:20 am

### Re: Partial Pressure

If you decrease the volume of a system, the same number of particles (or moles of a substance) will suddenly have more opportunities to collide (the frequency of their collisions will increase), which will increase the pressure of the system. The system will want to nullify this change and return to its state of equilibrium, and will subsequently lean towards the side that has less moles (and automatically, lower pressure), in which case the forward reaction would end up being favored (2 moles of gas vs. 3).