1. 10.3 – NOTES Gas Laws

2. II. The Gas Laws
A. The nature of gases dependent on temperature, pressure, # of gas particles present and the volume of the gas sample;
Standard conditions: 0.00°C and 1.00atm pressure; one mole of any gas occupies a volume of 22.4L

3. B. Boyle’s Law PV = constant temperature is constant!
At constant T, as the pressure increases, the volume of a gas decreases. This is a(n) inversely proportional relationship. Downward curve on a graph

4. Examples: PV = constant P1V1 = P2V2
The volume of a gas at atm is mL. What is the new volume if pressure is increased to 1.86 atm?
P1 = atm V1 = 300.0mL P2 = 1.86 atm V2 = ?? (158mL)

5. How much pressure is needed to decrease the volume of a gas from 4
How much pressure is needed to decrease the volume of a gas from L to L if the initial pressure is atm?
P1 = ?? V1 = L P2 = 0.980atm V2 = 4.00L

6. C. Charles’ Law V/T = constant pressure is constant
At constant P, as the temperature increases, the volume of a gas increases. This is a(n) directly proportional relationship.
Temperature MUST be in Kelvin;
plot on a graph is a straight line;
extrapolate line – volume = °C = O°K; this temp is referred to as absolute zero = lowest possible theoretical which all motion of gas particles ceases;

8. Examples: V1/T1 = constant V1/T1 = V2/T2
If a gas occupies a volume of 2.32 L at 40.0°C, what is the new volume is the temperature is increased to 75.0°C?
V1 = 2.32 L T1 = 40.0°C (313K) V2 = ? (2.58 L) T2 = 75.0°C (348K)
A gas sample’s volume is increased from 0.67 L to 1.12 L. If the initial temperature was 89.0°C, what is the final temperature (in °C)?
V1 = 0.67 L T1 = 89°C (362K) V2 = 1.12 L T2 = ? (332°C (605K))

9. D. Gay-Lussac’s Law P/T = constant
At constant V, as the temperature increases, the pressure of a gas increases. This is a(n) directly proportional relationship. Temperature be MUST in Kelvin!

10. Examples: P1/T1 = constant P1/T1 = P2/T2
What is the final pressure on a system if the temperature is changed from 22.0°C to 60.0°? (The initial pressure was 3.20 atm.)
P1 = 3.20 atm T1 = 22.0°C (295K) P2 = ? (3.61atm) T2 = 60.0°C (333K)
 If the pressure of a gas at constant volume is 2.56 atm at 35.6°C, what will the temperature be if the pressure is reduced to 1.12 atm?
P1 = 1.12 atm T1 = ? (-138°C ( 135K)) P2 = 2.56 atm T2 = 35.6°C (308.6K)

11. III. The Combined Gas Law and Avogadro’s Principle
A. The Combined Gas Law Can be used to help remember individual gas laws!!
This is a combination of Boyle’s Law, Charles’ Law and Gay-Lussac’s Law: Temp MUST be in Kelvin
Examples: P1V1/T1 = P2V2/T2

12. Examples: P1V1/T1 = P2V2/T2
A sample of Neon gas occupies a volume of 30.0 mL at STP, what is the new pressure if the temperature is increased to 30.0°C and the volume is decreased to 20.0 mL?
V1 = 30.0 mL V2 = 20.0 mL
P1 = 1.00 atm P2 = ? (1.66 atm)
T1 = 0.00°C (273K) T2 = 30.0°C (303K)

13. What is the volume of a sample of gas at 80. 0°C and 4
What is the volume of a sample of gas at 80.0°C and 4.34 atm, if the volume was 2.00 L at 30.0°C and 1.09 atm?
P1 = 1.09 atm P2 = 4.34 atm
T1 = 30.0°C (303K) T2 = 80.0°C (353K)
V1 = 2.00 L V2 = ? (0.58 L)

14. Correct to STP: 326 mL at 387K and 768 mmHg (This means find the volume at STP)
P1 = 768 mmHg (= 1.01 atm) P2 = 760 mmHg (= 1 atm)
T1 = 387 K T2 = 273 K
V1 = 326 mL V2 = ? (232 mL)