Question

Under which conditions does the molar volume of a gas decrease?

at 273 K and at 2.0 atm
at 273 K and at 0.5 atm
at 409.5 K and at 1.0 atm
at 546 K and at 2.0 atm

Answer 1

PV= nRT
V= nRT/P
ignore n and R so

V= T/P

Answer 2

check out all the values now

Answer 3

136.5
546
409.5
273

Is it the first choice since it is the smallest?

Answer 4

i guess thats how it is

Answer 5

tho word 'decrease' kinda confuses me
since how do we know if it decreased not if we don't know the original amount <.<

Answer 6

Well thank you. :)
Mind helping with a few more by chance?

Answer 7

oh wait

Answer 8

wait a sec
try this one
V/n= RT/P

V/n= this is actually molar volume, i ignored n since its 1 but then i also ignored R
try putting R values also

Answer 9

i think if the result is less the 22.4 L that means it decreases

Answer 10

That would make sense, and so that still leaves the first answer as correct.

Answer 11

and answer is still first one lol

Answer 12

yes :)

Answer 13

You wouldn't happen to know how to solve this would you?:

According to the equation 2Na + 2H2O mc012-1.jpg 2NaOH+H2, what mass of Na is required to yield 22.4 L of H2 at STP? (The atomic mass of Na is 22.99 u.)
1.00 g
2.00 g
23.0 g
46.0 g

(I could close this question and open a new one if you prefer.)

Answer 14

i think there was a picture?

Answer 15

2Na + 2H2O --> 2NaOH+H2
i see

Answer 16

well look there is formula
volume= mole * 22.4 L
so first thing lets find mole of H2

Answer 17

volume is given as 22.4 , so put it into the formula and get the mole
(don't get confused 22.4 in formula is STP condition, another 22.4L is given volume for H2)

Answer 18

after you find a mole of H2 use this formula
\[\frac{ mole~of~H_2 }{ coefficient~of~H_2 }=\frac{ mole~of ~Na }{ coefficient~of~Na }\]

Answer 19

u will know mole of H2 and coefficient from reaction
u need to find mole of Na and you know coefficient from reaction

Answer 20

clear till now?

Answer 21

Yeah sorry about that. I forget that the arrows don't copy correctly.
and give me just a minute. I'm trying to let it all sink in. :)

Answer 22

okay np

Answer 23

sorry gtg
i hope u get the upper part
its simple ratio thing we've done before

Answer 24

I've got it now. Thank you for your help. :)

Answer 25

after this use mole= mass/Molecular mass
so mass = mole*Molecular mass
mole- u just found
molar mass -given in the question
thus find mass

Answer 26

you are welcome :)