The Combined Gas law
P1xV1 = P2xV2
T1
T2
P=pressure
V=volume T=temperature in kelvin
The volume of gas filled balloon is 30.0L at 313. O K and 153.0 kPa pressure, what would be
the volume at standard temperature and pressure (STP)? T2 & P2
V1=
T1=
P1=
V2=
T2=
P2=
P1V1 = P2V2
T1
T2
Solve by isolating the unknown (V2)
P1 V1 = P2 V2
T1
T2
Step 1 label P1&2 for pressure, V1&2volume & T1&2 for =temperature in kelvin
V1
T1
P1
The volume of gas filled balloon is 30.0L at 313. O K and 153.0 kPa pressure, what would be the
volume at standard temperature and pressure (STP)? T2 & P2 Standard Temperature is
0 degrees Celsius but needs to be changed to Kelvin by adding 273 to 0 degrees Kelvin 273 K
T2. Standard Pressure is 1 Atm or 760 mmHg or 101.3 kPa. Since P1 is in kPa lets use 101.3
kPa P2
Step 2 V1= 30.0 L
T1= 313.0 K
P1= 153.0 kPa
V2=?
T2= 273 K
P2= 101.3kPa
Step 3 manipulate the formula to isolate V2
P1V1 = P2V2
T1
T2
P1 V1 = P2 V2
T1
T2
Multiply both sides of the equation by P2 and T2. Whatever you do to one side of the
formula do to the other.
P1 V1 = P2 V2 T2
T1
P2 T2
T2 P1 V1 = P2 V2 T2
P2 T1
P2 T2
= V2 = T2(P1)V1
Step 4 Plug in numbers V2 = 273.0K (153.0kPa) 30.0L = 3.9 L
101.3kPa (313.0K)
P2 (T1)