How to use Combined Gas Law to solve this?

Question

10.0 liters of oxygen are contained in a diver's tank at 20.0C and 2.0 atm pressure. What is the pressure when the tank is left exposed to the sun and it is heated to 45C?

Ok--I know that [(Pressure1*Volume1)/Temperature1] = [(Pressure2*Volume2)/Temperature2]

but how would I solve this? I don't know what the volume increases to, so is this solvable?

Answer 1

The volume does not change because the gas is contained in the tank. So (P1*V1)/T1=(P2*V2)/T2. Solving for P2:
P2=(P1*V1*T2)/(T1*V2)
V1=V2 so they cancel
P2=(P1*T2)/T1
P2=(2*(273+45))/(273+20)=2.17 atm

ps: divers use air not pure oxygen and the tank is charged to over 2000 psi (136 atm)

Answer 2

2.0 x 10.0 / 293 = P2 x 10.0 / 318
(temperature must be in kelvins, so 273 is added to the degrees celsius)

P2 = 2.2 atm

this makes sense because as temperature increases, pressure increases

Answer 3

PV = nRT, so your formula is correct with no change in n (for an ideal gas, close enough here).
Since you have P1, V1, T1 and V2 (=V1) and T2. P2 is the only variable remaining, with no freedom. so P2 = P1(T2/T1) in K or other absolute units.

Answer 4

P1 = n.R.T1/V
P2 = n.R.T2/V

P2/P1 = T2/T1