Original Volume = 125ml. Find new volume if Pressure changes from 700-500 torr, temp changes from 325-273K...

The original volume is 125 mL. Find the new volume if the pressure changes from 700 torr to 500 torr, the temperature changes from 325K to 273 K, and the number of moles changes from 0.267 moles to 0.375 moles.

A. 147 mL
B. 206 mL
C. 105 mL
D. 53.4 mL

for some reason my assignment says nothing about moles so i dont know how to calculate it, i know the rest but if you could explain the relationship of moles to volume/pressure/temp that would be awesome thanks! =) and plz give the answer...

There is something wrong with the statement of this problem.

At the beginning there is said to be: 700 torr, 325K and 0.267 moles.
Using the ideal gas law "PV = nRT" the volume under those conditions would be:
V = nRT / P = (0.267 mol) x (62.36367 L Torr /K mol) x (325K) / (700 torr) = 7.73 L

7.73 L is very different from 125 mL, so either some of these numbers are wrong or the ideal gas law doesn't apply. In either case this problem can't be solved as it stands.

Here your're working with P, T, and V ...Moles are not necessary in this case.

Combined Gas Law. P1V1T2 = P2V2T1

700torr x 125mL x 273K = 500torr x V2) x 325K

V2 = (700torr x 125mL x 273K) / 500torr x 325K
V2 = 23,887,500 / 162,500 = 147mL (Choice 'A').

PV = nRT

PV/nT = P'V'/n'T' = R

(I used primes, you can use P1 and P2, etc.)