Question

A 364-mL container holds 0.146 g of Ne and an unknown amount of Ar at 35°C and a total pressure of 624 mmHg. Calculate the moles of Ar present.

Answer 1

@iPwnBunnies

Answer 2

Ok, so in this container, we have a mixture of neon and argon. However, both gases experience the same volume and temperature. We will need to find the total amount of moles in the mixture.

Answer 3

Ideal Gas Equation: PV = nRT, rewrite for n, which is # of total moles of mixture.
n = (PV)/(RT)
So, in this problem, we'll have to use a different form of R. R = 0.08206 L-atm/mol-K

Answer 4

ok i know v= .364
T= 308.15K
P=.8211
and now R=0.08206

Answer 5

We have to do some conversions with the given quantities.
V = 364 mL (1L/1000mL) = 364 * 10^-3 L
P = 624 mmHg (1atm/760 mmHg) = ?? atm [Please calculate this lol]
T = 35 degrees C + 273.15= ?? K [calc this too]

Answer 6

way ahead of ya lol. but idk what to do with the .146 grams cause thats Ne and we need to find Ar

Answer 7

Did you find the total # of moles? I'll let you do all the calculations.

Answer 8

Hold on, I just wanna know the total moles first.

Answer 9

I'll just skip ahead then, assuming we have total moles...

We need to find how many moles of Ne are in the mixture.
moles = (mass)/(molar mass). Can you do that?

Answer 10

i did .146/20.179 and it is .0072 moles

Answer 11

now what?

Answer 12

Great! So, moles of Ar = total moles - moles of Ne! That is all. :)

Answer 13

so um im confused. what do i do now?

Answer 14

Well, did you find the total moles from the beginning?
n = (PV)/(RT). Plug in those values that you typed out.

Answer 15

n = how many moles of gas are in the container.

Answer 16

n=84.61

but why did i do .146/20.179?

Answer 17

That's how many moles of neon are in the container. It's part of the total amount of gas in the container.

Answer 18

And the total number of moles is actually 0.118 moles.
Soooooo
moles of Argon in the container = total moles (n) - moles of Neon

Answer 19

So, mol Ar = 0.118 mol - 0.0072 mol = 0.111 mol Ar

Answer 20

waiiiiit whered you get 0.118?

Answer 21

0.118 was the total number of moles in the mixture. You found the wrong number (you said it was 84.62 mol I believe).

Answer 22

._. really? my hard work down the drain lol

Answer 23

(.08206)(308.15)
-------------- = n
(0.8211)(0.364)

isn't this right?

Answer 24

Lol, just go back to the top:
n = [(0.8211 atm)(0.364 L)]/[(0.08206 L-atm/mol-K)(308.15 K)]

Answer 25

Nooo, you flipped the fraction.
n = (PV)/(RT)

Answer 26

heheh oooops!

ok but .111 isnt the answer right?

Answer 27

Yes, 0.118 is the total amount of moles of gas in the container. We found the amount of moles of neon in the container, 0.0072 mols. The amount of Ar is the difference between them: 0.118 mol - 0.0072 mol = 0.111 mol of Argon

Answer 28

it says i got it wrong lol

Answer 29

Did you type out the right values at the very beginning?

Answer 30

.0046 is the answer

Answer 31

Hold on.

Answer 32

ya .0118-.0072=.0046 :D

Answer 33

Ffs, I just got that too. I'm so sorry. :/

Answer 34

Can't believe I got 0.118 twice before. Unreal.

Answer 35

lol dont be! i corrected it! see you taught me and i caught a mistake xD THANK YOU SOOOO MUCH! YOURE A LIFESAVER

Answer 36

No prob lol.