1. Pressure Conversions 1 atm = 1.01325 x 105 Pa 1 bar = 1 x 105 Pa
1 millibar (mb) = 100 Pa
1 atm = bar
1 atm = 760 torr
1 torr = 1 mm Hg

2. Section 8.7, pp

4. Boyle’s Law Change volume (V) and the pressure (P) will change
(assuming that temperature and the number of molecules are constant)
Boyle’s Law
PV = constant
Pressure and Volume are inversely proportional
P1V1 = P2V2

5. A gas occupying a volume of 725mL at a pressure of 0
A gas occupying a volume of 725mL at a pressure of atm is allowed to expand at constant temperature until its pressure reaches atm. What is the final volume?
(725 ml)(0.970 atm) = (V2)(0.541 atm)
V2 = ml or L

6. Change the amount of gas (n) and the volume (V) will change
(assuming that temperature and pressure constant)
Avogadro’s Law
n  V
Number of Moles and Volume are proportional
V V2
n n2 =

8. Change the temperature (T) and the pressure (P) will change
(assuming that the volume and number of moles are constant)
Gay-Lussac’s Law
T  P
Temperature and Pressure are proportional
P P2
T1 T2 =

9. An aerosol can is under a pressure of 3. 00 atm at 25C
An aerosol can is under a pressure of 3.00 atm at 25C. Directions on the can caution the user to keep the can in a place where the temperature does not exceed 52C. What would the pressure of the gas in the aerosol can be at 52C?
3.00 atm X atm
298 K K =
X = 3.27 atm

10. Charles’ Law Change the temperature (T) and the volume (V) will change
(assuming that the pressure and number of moles are constant)
Charles’ Law
T  V
Temperature and Pressure are proportional
V V2
T T2 =

11. A sample of neon gas has a volume of 752mL at 25C
A sample of neon gas has a volume of 752mL at 25C. What volume will the gas occupy at 50C if the pressure remains constant?
752 ml X ml
298 K K =
X = 815 ml

12. What we find is that everything is interrelated…
The combined Gas Law
n  = constant
Such that P1V1 P2V2
T T2 PV T =

13. A He filled balloon has a volume of 50. 0L at 15C and 820mmHg
A He filled balloon has a volume of 50.0L at 15C and 820mmHg. What volume will it occupy at 650mmHg and 10C?
(50.0 L)(820 mmHg) = (X L)(650 mmHg)
(288 K) (283 K)
X = 62.0 L

14. PV = nRT Ideal Gas Law! PV n  = constant T
By defining the constant we can convert the proportionality into “workable” equation
PV = nRT
R is a constant which changes according to units, See Table 8.1 on page 401
R = L.atm/mol.K R = J/mol.K

15. Ideal Gas Conditions Negligible Interactions Negligible Particle Size
High Temperature
Low Pressure

16. Standard Temperature and Pressure (STP) 0oC 1 atm
Under standard conditions, what is the volume of 1.00 mol of gas?
PV = nRT
(1 atm)( V ) = (1 mol)( L.atm/mol.K)(273 K)
V = 22.4 L

17. How many moles of gas are in my 600 ml Pepsi bottle?
(assume that the room temperature is 22oC)
PV = nRT
(1 atm)
(0.6 L)
= n
( L.atm/mol.K)
(295 K)
n = mols