Lydia F. answered 01/18/22
Doctor of Pharmacy Specializing in Chemistry (10+ years experience)
Hi Sarah!
This is a Combined Gas Law question. The Combined Gas Law tells us how an ideal gas will change if we alter the pressure, volume, and/or temperature at a constant amount of moles. The equation is as follows:
P1V1 = P2V2
T1 T2
Where:
P1 is the initial pressure and P2 is the new pressure
V1 is the initial volume and V2 is the new volume
T1 is the initial temperature and T2 is the new temperature
Note that the temperature must be in Kelvin (so if it's in Celsius, convert by adding 273.15)
P1 and P2 must be in the same units
V1 and V2 must be in the same units
Now let's look at your problem!
1) Write down your givens:
V1 = 24 L V2 = ?
T1 = 273 K T2 = 388 K
P1 = 1.0 atm P2 = 3.0 atm
2) Make sure everything is in the correct units:
Temperature is in Kelvin? Check!
P1 and P2 have the same units? Check!
Since V1 is in liters, our V2 will also be in L.
3) Plug in and solve for V2:
P1V1 = P2V2
T1 T2
(1.0 atm)(24 L) = (3.0 atm) V2
273 K 388 K
Rearranging the above, we get:
V2 = (1.0 atm)(24 L)(388 K)
(273 K)(3.0 atm)
V2 = 11.36996 L
4) Use the correct significant figures and units:
When multiplying or dividing, we look for the least number of significant figures. Our volume and pressure values are given to us with 2 sig figs while our temperatures have 3 sig figs. Since 2 < 3, our final answer will have 2 significant figures.
Therefore, our final answer is 11 L
Hope this helps! :)
Jaden G.
Just to ask, how is the pressure-value considered two sig-figs when it shows only one non-zero number, or is the presence, of a decimal and tenth-spot zero, capable of affecting this?06/24/24

Lydia F.
06/24/24
Sarah K.
This makes sense, thank u sm01/18/22