Can anyone help me out with this problem?

We have 45 liters of oxygen at STP. What would be the temperature of the oxygen if we subject it to a pressure of 50 psi and find the volume changes to 38 liters?


This post was edited by JoeyMorgan619 on Nov 16 2013 07:35pm

2. CO2 diffuses to fill a container in 3.2 minutes. Another gas diffuses to fill the same container in 5 minutes. What is the molecular weight of the second gas?

3. We find that we have 3.8 grams of vapor in a 350mL flask. If the temperature at which we collected the gas is 100 degrees C, and the barometric pressure is 31 inches of mercury, what is the molecular weight of the gas?

Would also be nice

We use the ideal gas law, PV = nRT. Since in this example (nR) is a constant value, we can express the ideal gas law in the following way:

PV = nRT
PV/T = nR = constant.

Now, we can further manipulate the law and equate the following:

P1V1/T1 = P2V2/T2 (Combined gas law)

You can use this type of equation not just for constant n problems but for constant T, constant V and constant P problems. In this problem, only n and R remain constant.
In the combined gas law, x1 refers to initial x and x2 refers to final x.

P1 = 0.987 atm (standard pressure)
V1 = 45 litres
T1 = 273.15 K (standard temperature)
P2 = 50 psi = 3.4 atm
V2 = 38 litres
T2 = unknown

Substituting into the combined gas law equation:

(0.987*45/273.15) = (3.4*38/T2)
0.1626 = 129.2/T2
T2 = 129.2/0.1626
= 794.58 K


Been years since I've done this but that result is accurate with experimental observations i.e. temperature of a gas is observed to increase with increasing pressure and decreasing volume.

For the first question, you'll want to use the ideal gas law PV = nRT

Be careful when plugging in your values for each of the respective variables, make sure they cross out (use the right R)

hint for the first one: 22.4 L at STP