## n/V = concentration

$PV=nRT$

Cristian Cortes 1L
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### n/V = concentration

There was a part in lecture 2 where the professor talks about the formula P=nRT/V and how n/V is just concentrate can anyone explain this ?

Aydin Karatas 1F
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### Re: n/V = concentration

That part of the lecture was talking about how you can convert between partial pressures and concentrations for gases. $PV=nRT$
is the ideal gas law. If we rearrange it to $P=\frac{nRT}{V}$, we notice that $n/V$ is just concentration ($M=\frac{mol}{L}$). Therefore, if we ever need to convert partial pressure to concentration, we can use the formula $Concentration=\frac{P}{RT}$.

Hope this helps!

Jack Kettering 3D
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### Re: n/V = concentration

Concentration by definition is moles over liters and n in the ideal gas equation represents moles and volume is liters therefore n/V is equal to concentration

Sana Nagori 2H
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### Re: n/V = concentration

It's just rearranging the equation and realizing that molarity=concentration= mol/L

Emily Tieu 2K
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### Re: n/V = concentration

As mentioned, n/V is a simple way for us to find the concentrations for gases by manipulating the ideal gas law. In PV = nRT, we know the variable n represents moles and the variable V represents volume. Just make sure V is in Liters since the units for concentration are typically mol/L.

Rachel Kho Disc 2G
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### Re: n/V = concentration

Concentration is simply moles/liters, which, if you remember from 14A is the same as moles of solute(n)/volume of solution(v), which is equal to molarity(M).

sabrina ghalambor 2J
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### Re: n/V = concentration

n/V is rearranging the variables to represent concentration because n=mols of x and V is liters!

Tiao Tan 3C
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### Re: n/V = concentration

Accoding to the ideal gas law, PV=nRT. If we divide both sides with V, we could have the equation for pressure: P=(nRT)/V
Because n (in moles) divided by volume V(in liters) would result in concentration (in moles per liter), we could substitute n/V in the equation with concentration.
Therefore, P = concentration*(RT)

Uyenvy Nguyen 1D
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### Re: n/V = concentration

concentration is mol/liters, and n represents the number of moles and V represents volume, which can be measured in liters

Pranav Daggubati 3C
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### Re: n/V = concentration

As n is the number of moles and V is volume in liters, it is easy to see that n/V is just molarity, which is a measure of concentration.

Tikva Cohen 1K
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### Re: n/V = concentration

Tiao Tan 3C wrote:Accoding to the ideal gas law, PV=nRT. If we divide both sides with V, we could have the equation for pressure: P=(nRT)/V
Because n (in moles) divided by volume V(in liters) would result in concentration (in moles per liter), we could substitute n/V in the equation with concentration.
Therefore, P = concentration*(RT)

This answer was very helpful to me and very well explained, thank you!

since n/v just converts to the units of moles/liters, you can assume it's concentration

Margaret Xu 3C
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### Re: n/V = concentration

Hello! We know molarity = moles of solute (mol) / volume of solution (L). When we rearrange the ideal gas law so that n/V, we realize that this is the same thing as mol/L, which is concentration.

Aarushi Verma 2I
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### Re: n/V = concentration

Hi! Since molarity (M) is defined as the concentration over the volume, we can manipulate our ideal gas equation to get (n/v) on one side and get P/rt on the other side. This is super helpful to go between molarity and pressure especially since we use a lot of gases in chemical equilibrium.

Simi Kapila_3E
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### Re: n/V = concentration

n=moles and V=volume, which can be liters. And since concentration is mol/L, n/V can mean the exact same thing.

Nancy Yao
Posts: 62
Joined: Wed Sep 30, 2020 9:38 pm

### Re: n/V = concentration

Aydin Karatas 1F wrote:That part of the lecture was talking about how you can convert between partial pressures and concentrations for gases. $PV=nRT$
is the ideal gas law. If we rearrange it to $P=\frac{nRT}{V}$, we notice that $n/V$ is just concentration ($M=\frac{mol}{L}$). Therefore, if we ever need to convert partial pressure to concentration, we can use the formula $Concentration=\frac{P}{RT}$.

Hope this helps!

This helps so much! Thanks for explaining.

Nan_Guan_1L
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### Re: n/V = concentration

besides the discussion above, you can also think of it similar to the density formula: density = mass / volume. In this case, mass would be similar to n and concentration would be like density, if that helps understand the equation better.

BKoh_2E
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### Re: n/V = concentration

Remember that molarity and concentration are basically the same thing. The formula for molarity is M=mol (n)/volume (L). So for the formula PV=nRT, we can divide both sides by volume and get P=MRT.

apurva-3E
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### Re: n/V = concentration

You can rearrange the equation pv=nrt and turn n/v into concentration.

305405193
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Joined: Wed Sep 30, 2020 9:47 pm

### Re: n/V = concentration

so let's say there is a problem where they provide the mols and they are in a certain number of L in a container you would have to find the concentration with is basically mol/L in order to then proceed with the problem?

Jerry_T
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Joined: Wed Sep 30, 2020 9:46 pm

### Re: n/V = concentration

305405193 wrote:so let's say there is a problem where they provide the mols and they are in a certain number of L in a container you would have to find the concentration with is basically mol/L in order to then proceed with the problem?

That depends on the problem but mol/L is a common measurement of concentration in chemistry. In chemical equilibrium questions where you use ICE tables, you would have to use concentration (mol/L).