PV=nRT and concentration


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Sameer Gupta 2F
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PV=nRT and concentration

Postby Sameer Gupta 2F » Fri Jan 08, 2021 11:42 am

I am still confused as to why n/V gives us Molarity or concentration. Can someone enlighten me?

ellenulitsky Dis 1I
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Re: PV=nRT and concentration

Postby ellenulitsky Dis 1I » Fri Jan 08, 2021 11:46 am

Molarity is given by doing (mol/volume). n is the number of moles, while V stands for volume so by doing n/V, it gives molarity, which is equivalent to the concentration(why we include molarity inside [] not only moles! Hope this helps!

Aliya 1H
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Re: PV=nRT and concentration

Postby Aliya 1H » Fri Jan 08, 2021 11:46 am

Hey! Molarity (M) is moles/liter. n/V is moles/volume and volume would be in liters, thus giving us molarity.

BKoh_2E
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Re: PV=nRT and concentration

Postby BKoh_2E » Fri Jan 08, 2021 11:59 am

Molarity and concentration are the same for the purpose of these problems. Just remember that molarity is mol/volume (L), and "n" refers to moles.

Sai Ramadas 1J
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Re: PV=nRT and concentration

Postby Sai Ramadas 1J » Fri Jan 08, 2021 12:44 pm

n is the number of moles in our experiment, while V stands for volume (often in terms of liters). When we do n/V, we get moles per liter, which is the unit we use for concentration.

Stephen Min 1I
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Re: PV=nRT and concentration

Postby Stephen Min 1I » Fri Jan 08, 2021 1:38 pm

n represents the moles while L represents Liters/ volume of the solution, which then gives us mol/L or molarity.

Inderpal Singh 2L
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Re: PV=nRT and concentration

Postby Inderpal Singh 2L » Fri Jan 08, 2021 2:33 pm

Molarity = mol/L
And n, in this case, represents mol
V would be liters(L)

Yashvi Reddy 1H
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Re: PV=nRT and concentration

Postby Yashvi Reddy 1H » Fri Jan 08, 2021 3:44 pm

Hi! Good question, and I agree with the answers above. Since we know that M = mol/L (where M is molar concentration, mol represents moles, and L represents volume in liters), after substituting in "n" for the number of moles and "V" for the volume, we can see that concentration equals n/V. I hope this was helpful! Have a wonderful weekend!

SophiaJenny3I
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Re: PV=nRT and concentration

Postby SophiaJenny3I » Fri Jan 08, 2021 5:34 pm

Hi! So, in the PV = nRT equation, here are what all the variables represent which will help.
P = pressure in atm, V = volume in L, n = moles, R = gas constant ( 8.206 x 10-2 L·atm·K-1·mol-1, for example), and T = temperature in K.
Most important thing about figuring this out, is understanding Molarity = mol/L. Therefore, through the variables we know, we want to rearrange the equation so we have mol/V = the other variables. In other words, n/V = P/RT. Since n = moles and V is in liters, this is molarity. So, if it helps, you can just change n/V to M. Hope this helps!!

Violet Kwan 3H
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Re: PV=nRT and concentration

Postby Violet Kwan 3H » Fri Jan 08, 2021 6:24 pm

Molarity is a way to describe the concentration specifically in terms of moles per liter. So, the "n" represents moles and "V" represents the volumes in liters. Because these variables are present in the equation, we can rearrange it in order to solve for the concentration.

Jason_John_2F
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Re: PV=nRT and concentration

Postby Jason_John_2F » Sat Jan 09, 2021 2:03 am

we can change the n/v into concentration because the definition of molarity is just moles/liters so they are substitutable

Krish_Ajmani_3J
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Re: PV=nRT and concentration

Postby Krish_Ajmani_3J » Sat Jan 09, 2021 12:21 pm

Concentration is given by molarity or moles/Liters. Dividing both sides of the equation by V gives us n/V on the right side. Since n=moles and volume can be calculated in liters, n/V=molarity or concentration.

Sophia Spungin 2E
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Re: PV=nRT and concentration

Postby Sophia Spungin 2E » Sat Jan 09, 2021 1:18 pm

I found it useful to think of concentration in this case as Molarity. Molarity is calculated by taking the number of moles of a solute and dividing by the volume of the solution, or n/V. in the ideal gas law, solving for n/V is thereby solving for concentration.

Margaret Xu 3C
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Re: PV=nRT and concentration

Postby Margaret Xu 3C » Sun Jan 10, 2021 3:40 am

Molarity, or molar concentration, is defined by the number of moles of solute per liter of solution, mol/L. In the ideal gas law, PV = nRT, n is the number of moles and V is volume, so n/V can be rewritten as concentration (mol/L). I hope this explanation wasn't too confusing!

Sandy Lin 1L
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Re: PV=nRT and concentration

Postby Sandy Lin 1L » Sun Jan 10, 2021 9:33 am

Concentration refers to the amount of a substance in a solvent. This is why it is calculated by the number of moles of the substance divided by the volume. You would use this when you want to convert between Kp and Kc. If you’re ever confused it’s good to know the units that are involved in the calculation because they would need to cancel out in the end.

Colin Squire 3B
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Re: PV=nRT and concentration

Postby Colin Squire 3B » Sun Jan 10, 2021 9:51 am

If we go back to 14a, recall the molarity equations, it was the moles divided by the volume. This is essentially the same thing except for being apart of a larger equation.

305572629
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Re: PV=nRT and concentration

Postby 305572629 » Sun Jan 10, 2021 10:20 am

molarity, usually in brackets [] like when we try to calculate K or Q by dividing concentration (molarity) of products / concentration (molarity) of reactants, is a measure of moles per liter of chemicals in these reactions. So for the purpose of K and Q problems, the molarity and moles are usually the same because the volume tends to be 1 L.

Sameer Chowdhury 3C
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Re: PV=nRT and concentration

Postby Sameer Chowdhury 3C » Sun Jan 10, 2021 1:34 pm

As everyone else has said, given that molarity is simply moles/liter, liters being a a unit of volume, n/V provides us the molar concentration.

Mari Williams 1K
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Re: PV=nRT and concentration

Postby Mari Williams 1K » Sun Jan 10, 2021 1:40 pm

Can you calculate K using all partial pressures, or do you need to convert to concentration?

Abhinav Behl 3G
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Re: PV=nRT and concentration

Postby Abhinav Behl 3G » Sun Jan 10, 2021 6:14 pm

Molarity is calculated by dividing the moles of a particular substance by the volume of the reaction vessel. When looking at the ideal gas law, n=moles and V=volume, so n/V will give us moles/volume, aka the molarity of that substance.

Lauren Mungo 1K
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Re: PV=nRT and concentration

Postby Lauren Mungo 1K » Sun Jan 10, 2021 6:17 pm

The definition of molarity is moles per liter. n represents moles and v is the volume which is expressed in liters. So by dividing n/V you get moles/liter which is molarity.

Chance Herbert 3A
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Re: PV=nRT and concentration

Postby Chance Herbert 3A » Sun Jan 10, 2021 6:21 pm

Molarity is measured in moles/Liter. In the expression n/V, n represents moles, and volume (V) is measured in liters. Dividing moles by liters provides the units of Molarity or concentration!

Tobie Jessup 2E
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Re: PV=nRT and concentration

Postby Tobie Jessup 2E » Sun Jan 10, 2021 6:38 pm

n/V is just moles/volume. It also confused me at first but paying close attention to the actual units it helpful!

t_rasul2I
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Re: PV=nRT and concentration

Postby t_rasul2I » Sun Jan 10, 2021 8:59 pm

If you refer back to 14A, you will remember we consider molarity or concentration with mols divided by volume. n/V is the algebraic representation of mols divided by volume.

Jack Kettering 3D
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Re: PV=nRT and concentration

Postby Jack Kettering 3D » Sun Jan 10, 2021 9:01 pm

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

Lily Mohtashami
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Re: PV=nRT and concentration

Postby Lily Mohtashami » Sun Jan 10, 2021 9:03 pm

n/V resembles moles/volume, n is the symbol for moles and V is the symbol for volume so together, n/v= molarity which is moles over volume.

Jose Miguel Conste 3H
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Re: PV=nRT and concentration

Postby Jose Miguel Conste 3H » Sun Jan 10, 2021 9:07 pm

because its moles over volume, that is the measurement for molarity, therefore n/V is molarity

Presley Gao 2C
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Re: PV=nRT and concentration

Postby Presley Gao 2C » Sun Jan 10, 2021 9:31 pm

Molarity (or concentration) is represented in moles / volume, which is the respective unit of measure for molarity (or concentration).


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