Question

A sample of gas with a mass of 8.40 g occupies a volume of 4.50 L at 298 K and 1.10 atm. What is the molar mass of the gas? Show all work used to find your answer. *Best answer gets medal, fan and testimony*

Answer 1

Use the ideal gas law, substitute in the definition of moles, solve for M, molar mass.

Ideal gas law: \(\sf PV=nRT\) moles: \(\sf n=\dfrac{m}{M}\)


\(\sf \huge PV=\dfrac{m}{M}RT\rightarrow M=\dfrac{mRT}{PV}\)

Answer 2

May you help me plug in the variables?

Answer 3

I can check it for you if you give it a try

Answer 4

Ok. Give me a second.

Answer 5

I have:

1.10*4.50 L = n(0.08206atm)(298K)

And that's all I can do. Unfortunately.

Answer 6

that's right!

you can now solve for n, then divide the mass 8.4 g by the moles.

Answer 7

the mass is given in the question, it's 8.4 grams

Answer 8

So it would be:

1.10 atm * 298 K = 24.45388
8.4 g / 24.45388 = 0.3435

Answer 9

not quite, first solve this equation:

1.10*4.50 L = n(0.08206atm)(298K)

divide the mass by the answer (moles)

Answer 10

4.95 = n(0.08206*298)
4.95 = n(24.45388)
4.95/24.45388 = 0.202421...
n = 0.202421

Answer 11

okay, looks good! now divide the mass by n

Answer 12

244.5398

Answer 13

There you go

Answer 14

WOOHOO! How would I properly write with sig figs?

Answer 15

all the numbers used have 3 sig figs, so make the answer have 3 figures.

Answer 16

244. Thank you so much! You're a life saver :D

Answer 17

that's not quite right. look at the fourth digit, you have to round up

Answer 18

Oh... 245, correct?

Answer 19

yeah. you should give this a look

https://www.physics.uoguelph.ca/tutorials/sig_fig/SIG_dig.htm

Answer 20

Will do.

Answer 21

Got it. Thanks :)

Answer 22

no problem!

Answer 23

@aaronq there is problem in this question

Answer 24

whats the problem?

Answer 25

should the answer be around 41 to 42 because we are dividing 8.4 by n

Answer 26

@aaronq

Answer 27

you're right, the answer is 41.4974933333333333

I guess this person plugged the numbers into the calc wrong

Answer 28

oh thank so much

Answer 29

np!

Answer 30

thanks for double checking lol

Answer 31

np!