Ch. 10 Gas Laws Notes Introduction
Standard Temperature and Pressure (STP)
P= 1 atm = 760 mmHg = 760 Torr = 101.325 kPa = 101,325 Pa
T= 0oC = 273.15 K
0 Kelvin is absolute zero
Volume units commonly are cm3 = ml
dm3 = L
1000 ml = 1 L
1000 ml = 1 dm3
1000 cm3 = 1 L
1000 cm3 = 1 dm3
Pressure units: atm = atmospheres
kPa = Kilopascals
mmHg = millimeters of Hg
Need to convert between all 3 Pressure Units
Example:
2.00 atm

mmHg
Or 2.00 atm

kPa
Need to convert to Kelvin from Celsius by adding 273.15
Example:
25.0 C +
For Gas Law problems
1st conditions
Initial conditions
Original conditions
=
Kelvin

2nd conditions
Final conditions
Next conditions

3rd conditions
Combined Gas Law: Because the formula is equal to a constant, it is possible to solve for a change in volume,
temperature, or pressure using a proportion:
PV/T = P1V1/T1 = P2V2/T2
Combines Boyle’s and Charles’ Laws
Temperature must be in Kelvin & Pressure units must match
Gas Law Laws
Different Laws have different variables held constant
If _____Constant, then__________Law
T  Boyles
If _____Constant, then__________Law P  Charles
If _____Constant, then__________Law V  Gay Lussac
If temperature is constant, then P * V = k at a specific temperature or P=
Or
P1V1 = k and P2V2= k, then P1V1 = k = P2V2
Example 1: A sample of gas has a volume of 171 cm3 at 0.999 atm. What is the volume if pressure changes to 1.20 atm?
P1=
V1=
V2= 201 cm3
if P
does V
and P
then
P2=
V2=
V
Example 2: A sample of gas has a volume of 250.0 ml at 760.0 mm Hg. What is the pressure if the volume changes to
350.0 ml?
Example 3: A sample of gas has a volume of 250.0 ml at 398 K. What is the volume if the temperature changes to
298 K?