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The Gas Laws. Directly proportional —as one variable goes up/down the other goes up/down. Both variable do the same thing. Indirectly proportional – as one variable goes up the other goes down. The two variable do the opposite thing. Boyle’s Law. P 1 V 1 = P 2 V 2 Temperature is constant
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Directly proportional—as one variable goes up/down the other goes up/down. Both variable do the same thing. • Indirectly proportional– as one variable goes up the other goes down. The two variable do the opposite thing.
Boyle’s Law • P1V1 = P2V2 • Temperature is constant • Pressure (P) and volume (V) are indirectly proportional
Example 1 A helium balloon was compressed from 4.0L to 2.5L at a constant temperature. If the pressure of the gas in the 4.0L balloon is 210 kPA, what will the pressure be at 2.5L? Given: V1 = 4.0L V2 = 2.5L P1= 210 kPa P2 = ? P1V1 = P2V2 (210 kPa) × (4.0L) = P2× (2.5L) P2 = 336 kPa ≈ 340 kPa
Example 2 A sample of neon gas occupies 0.200L at 0.860 atm. What will be its volume at 29.2 kPa pressure? 0.860 atm 101.3 kPa 1 atm P1V1 = P2V2 = 87.1 kPa Given: V1 = 0.200L V2 = ? P1= 0.860 atm P2 = 29.2 kPa (87.1 kPa) × (0.200L) = (29.2 kPa) × V2 V2 = 0.597L **Units must match for each variable (doesn’t matter which one is converted)
Charle’s Law • V1 V2 T1 T2 • Pressure is constant • Temperature must be in Kelvin • Volume (V) and temperature (T) are directly proportional =
Example 1 A gas ample at 40.0°C occupies a volume of 2.32L. If the temperature is raised to 75.0°C, what will the volume be, assuming the pressure remains constant? Given: T1 = 40.0°C = 313K T2 = 75.0°C = 348K V1= 2.32L V2 = ? V1 V2 T1 T2 2.32L V2 313 348 = = V2 = 2.58L
Example 2 A gas ample at 55.0°C occupies a volume of 3.50L. At what new temperature in kelvin will the volume increase to 8.00L? Given: T1 = 55.0°C = 328K T2 = ? V1= 3.50L V2 = 8.00L V1 V2 T1 T2 3.50L 8.00 328 T2 = = T2 = 750K
Gay-Lussac’s Law • P1 P2 T1 T2 • Volume is constant • Temperature must be in Kelvin • Pressure (P) and temperature (T) are directly proportional =
Example 1 The pressure of a gas in a tank is 3.20 atm at 22.0°C. If the temperature rises to 60.0°C, what will be the gas pressure in the tank? Given: P1 = 3.20 atm P2 = ? T1= 22.0°C = 295K T2 = 60.0°C =333K P1 P2 T1 T2 3.20 atm P2 295K 333K = = P2 = 3.61 atm
Example 2 A rigid container has a gas at constant volume at 665 torr pressure when the temperature is 22.0C. What will the pressure be if the temperature is raised to 44.6C? Given: P1 = 665 torr P2 = ? T1= 22.0°C = 295K T2 = 44.6°C =317.6K P1 P2 T1 T2 665 torr P2 295K 317.6K = = P2 = 716 atm