Ideal gas law problem?
A 19.9-L tank of carbon dioxide gas (CO2) is at a pressure of 7.80 x10^5 Pa and temperature of 21.3°C.
Find the number the moles of gas in the tank.
I worked out this problem several times and I kept getting .0625 moles, which is wrong. I know this is a simple problem but I'm doing something wrong. I converted celcius into Kelvins and I converted Pa into atm. Any help would be great!
Update:Oh I was using the wrong R value with atm! Thanks for the help!
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Verified answer
PV=nRT
P: 7.8x10^5 Pa = 7.698x10^-5 atm
V: 19.9 L
n: ?
R: 0.082 L atm/ mol K
T: 21.3C = 294.45K
n= (7.698x10^-5 atm) (19.9L)
------------------------------------------------
(0.082 L atm / mol K) (294.45 K)
= 6.34 mol
makes sure when you put the numbers into your calculator that you carefully input them in the correct way. it's a binary system and doesn't know what to do, you tell it what to do.
other than that, double check your conversions, I always use my calculator to check mine.
okay, I'll give it a try (assuming ideal gas)
PV=nRT
n=PV/RT
n=(7.8*10^2 kPa)(19.9L)/R(21.3+273)K
n= 503.57/R Pa-L/K
from the wikipedia: R=8.314472(15) L kPa K−1 mol−1
that looks like the correct R for the units we have except we need to convert to kPa
n=504/8.3= 6.06
I don't know if my arithmetic is any better than yours (and I played fast and loose with significant figures) but hopefully even if I did something wrong together we have a correct solution
good luck
T temperature to be measured on kelvin scale.. i.e. 19+273 ok and no of moles.. weight divided via molecular weight value of R 2 b chosen accordin to the instruments used for pressur en volume.. if u use atm-l then the value of R is 0.0821 if u use pascal-m^3 value is 8.314 and for calculation of warmth or capability in energy, value of R shud be approximated to 2