Major points and concepts
Pressure Conversions:
1 atm: 760 mmHg
1 atm: 14.7 psi
1 atm: 101,325 Pa
1 atm: 760 torr
Atmospheric pressure:
Combined Gas Law
Avogadro's Law:
Boyle's Law
Charles's Law:
Ideal Gas Law
Dalton's Law of Partial Pressure:
1 atm: 760 mmHg
1 atm: 14.7 psi
1 atm: 101,325 Pa
1 atm: 760 torr
Atmospheric pressure:
- results from the mass of the air being pulled toward the center of the earth by gravity (being pushed on us)
Combined Gas Law
- assumption: number of moles is constant
- it combines Boyle's and Charles's law
- P1V1/T1 = P2V2T2
Avogadro's Law:
- the relationship between the volume of a gas and the number of molecules present in the gas sample
- if the number of moles increases, then the volume should also increase
- temperature and pressure are constant
Boyle's Law
- focuses on the relationship between pressure and volume
- reducing volume, pressure increases
- increasing volume, pressure decreases
- pV=PV
- assumption: temperature is constant; moles of air is constant
Charles's Law:
- temperature is proportional to volume
- as temperature increases, volume increases
- as temperature decreases, volume decreases
- Vi/Ti = Vf/Tf
- absolute zero: an object tht exists can reduce its volume but can never have 0 volume or negative volume
Ideal Gas Law
- R= universal gas constant (0.08206 L atm/mol K
- P= pressure
- V= volume
- n= moles
- T= temperature
- PV=nRT
- assumption: the gas must be ideal
Dalton's Law of Partial Pressure:
- many gases contain a mixture of components
- total pressure exerted is the sum of the partial pressures of the gases present
- P(total) = P1 + P2 + P3
Example calculations
Combined Gas Law:
Boyle's Law:
Charles's Law:
Ideal Gas Law:
Answers:
P2 = [5.5 L] [ 101.3 KPa][300 K] = 111.3 KPa
[5.5 L] [273 K]
n=[ (1.00 atm) (56.2 L) ] / [ (0.08206 L atm mol¯1 K¯1) (273.0 K) ]n=2.50866 mol
2.50866 mol times 39.948 g/mol = 100. g
- Oxygen occupies a fixed container of 5.5L at STP. What will happen to the pressure if
the temperature rises to 300K?
Boyle's Law:
- A gas occupies 1.56 L at 1.00 atm. What will be the volume of this gas if the pressure becomes 3.00 atm?
Charles's Law:
- 600.0 mL of air is at 20.0 °C. What is the volume at 60.0 °C?
Ideal Gas Law:
- A sample of argon gas at STP occupies 56.2 liters. Determine the number of moles of argon and the mass in the sample.
Answers:
- Combined Gas Law:
P2 = [5.5 L] [ 101.3 KPa][300 K] = 111.3 KPa
[5.5 L] [273 K]
- Boyle's Law:
- Charles's Law
- Ideal Gas Law
n=[ (1.00 atm) (56.2 L) ] / [ (0.08206 L atm mol¯1 K¯1) (273.0 K) ]n=2.50866 mol
2.50866 mol times 39.948 g/mol = 100. g