## partial pressures

$PV=nRT$

Brian_Wu_3B
Posts: 93
Joined: Wed Sep 30, 2020 9:41 pm

### partial pressures

What do partial pressures really mean? Why can they be converted to concentrations? I'm just not quite understanding what the term means.

Chanel Mao 3D
Posts: 95
Joined: Wed Sep 30, 2020 9:52 pm
Been upvoted: 2 times

### Re: partial pressures

Partial pressures are basically the pressure of each gas if it were to occupy the container just by itself (the total pressure of a container of mixed gases is the sum of all the partial pressures of each gas). Since concentration is moles/liters, you can technically put moles of gas over liters. Hope this helps!

Aaron Akhavan-Dis1B
Posts: 94
Joined: Wed Sep 30, 2020 9:59 pm

### Re: partial pressures

Partial pressure is like the force exerted by a gas if it was just by itself in some volume. In PV=nRT, we can manipulate it to be: P/RT = n/v. n/V is concentration, and we can see that Pressure is proportional to concentration. 1/RT is our proportionality constant.

Posts: 96
Joined: Wed Sep 30, 2020 10:01 pm

### Re: partial pressures

Brian_Wu_3B wrote:What do partial pressures really mean? Why can they be converted to concentrations? I'm just not quite understanding what the term means.

The pressure of a mixture of gases is the sum of the partial pressures of the different gases in the mixture. So we're basically saying that all the gases in the mixture contribute a portion to the total pressure, or a partial pressure. When calculating your equilibrium constant either concentrations or partial pressures can be utilized depending on the components of the mixture so there is a relationship between Kp and Kc : Kp =Kc (RT)^(delta n)
delta n is the change in moles of gases.

SashaAnand2J
Posts: 90
Joined: Wed Sep 30, 2020 9:37 pm

### Re: partial pressures

Partial pressures are the molar fraction of a gas over total pressure in a container (from adding up the total moles of gas in the reaction). I believe in all of the examples concerning equilibrium, the total pressure is 1 atm.

Dylan_Nguyen_2C
Posts: 87
Joined: Wed Sep 30, 2020 9:41 pm

### Re: partial pressures

Each gas in an equilibrium reaction takes up space/volume, meaning that they each exert their own partial pressure by colliding with other particles and their container. The sum of all of these partial pressures results in the total pressure, which is the amount of pressure exerted on the container by all of the gases inside of it. We can convert partial pressures to concentrations because molar concentrations are measures of moles/liter, so we can calculate the concentrations of each gas in a reaction given their partial pressure by rearranging PV=nRT to n/V=P/RT. Hope this helps

Karen Zheng_2K
Posts: 88
Joined: Fri Sep 29, 2017 7:04 am

### Re: partial pressures

In comparison to total pressure, partial pressure is just the measured pressure of one gas if it were in a container by itself, as compared to it being in a mixture with other gases.

Nan_Guan_1L
Posts: 92
Joined: Wed Sep 30, 2020 9:59 pm

### Re: partial pressures

partial pressure is the gas pressure when this gas alone occupies the container at the same temperature. if it helps the total pressure of an ideal gas is the sum of all partial pressure of the gasses included.

Neel Sharma 3F
Posts: 96
Joined: Wed Sep 30, 2020 9:32 pm
Been upvoted: 1 time

### Re: partial pressures

One way to think of it is by comparing it to concentrations. Similar to how each element has its own unique concentration in a solution. Each element has its own unique partial pressure. Hope this helps!

t_rasul2I
Posts: 98
Joined: Wed Sep 30, 2020 9:38 pm

### Re: partial pressures

Partial pressure can be broken down into its words: partial because each gas exerts a fraction of the total pressure and pressure to represent pressure

Samir 3I
Posts: 43
Joined: Wed Sep 30, 2020 10:04 pm

### Re: partial pressures

I understand why we can convert between partial pressure and concentration but it seemed to me that prof Lavelle used them interchangeably in lecture. Can they be used interchangeably or does it just depend on the context and I just wasn't understanding the context he was using it in?

Chinmayi Mutyala 3H
Posts: 95
Joined: Wed Sep 30, 2020 9:50 pm

### Re: partial pressures

Partial pressures is the pressure of each individual gas. When all the partial pressures are added up, you get the total pressure. It can be convereted to concentration (which is measured in mol/L) using the ideal gas law: PV = nRT --> you solve to get n/V which would be mol/L.

Sondia Luong 1C
Posts: 89
Joined: Wed Sep 30, 2020 10:01 pm
Been upvoted: 1 time

### Re: partial pressures

Concentration would normally be used in equilibrium, but if the substances are in a gaseous state we would use partial pressure as the unit instead. They both represent the same thing!

Brandon McClelland3L
Posts: 89
Joined: Wed Sep 30, 2020 9:31 pm

### Re: partial pressures

The total pressure is the amount of pressure a mixture of gases has. The partial pressure of a gas within the mixture is the amount of pressure it contributes to the overall pressure.

Jaclyn Schwartz 1I
Posts: 101
Joined: Wed Sep 30, 2020 9:45 pm

### Re: partial pressures

Partial pressure is just the pressure the gas would have in the container if it was by itself. All the partial pressures add up to the total pressure of the container. But each gas is exerting its own pressure on the container. Hope that helps!