State Normal atmospheric pressure in five standard units 

1 atm
760 torr
101.3 kilopascals
14.7 lbs/square inch





An instrument, invented by Torricielli in 1643, which measures atmospheric pressure. An evacuated glass tube in which a column of mercury rises or falls with changing pressure. 


An instrument used to measure pressure of gases in a closed container. 

State three postulates of the KineticMolecular Theory of Gases 

1. Matter is composed of very small particles; a gas is mostly empty space.
2. Particles are in constant random motion.
3. Collisions are elastic.


State the formula for Graham’s Law of Diffusion. 

In a mixture of gases A, B:
;
(R_{A})(MW_{A})^{1/2} = (R_{B})(MW_{B})^{1/2}
;
MW = Molecular Weight
R = Rate of diffusion


Do heavy or light gases diffuse faster? 

Light gases diffuse faster. 


V_{1}/T_{1} = V_{2}/T_{2}
Volume and temperature have a direct relationship when pressure and moles of gas remain constant.
V = volume
T = Kelvin


Solve this problem:
At 300 K, a gas has a volume of 10 liters.
Find the volume at 400 K


Use Charles’ Law: V_{1}/T_{1} = V_{2}/T_{2}
V_{2} = 13.3 L



(P_{1})(V_{1}) = (P_{2})(V_{2})
Pressure and volume have an inverse relationship when temperature and moles of gas remain constant.
P = Pressure
V = Volume


A sample of gas has a volume of 25 L at 800 torr. Find the volume at 400 torr. 

Use Boyle’s law: (P_{1})(V_{1}) = (P_{2})(V_{2})
;
V_{2} = 50 L



P_{1}V_{1}/T_{1} = P_{2}V_{2}/T_{2}
;
Moles of gas constant
P = Pressure
V = Volume
T = Kelvin


Dalton’s Law of Partial Pressures 

In a gas mixture, the total pressure equals the sum of the partial pressures of each component.
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P_{total} = P_{1} + P_{2} + P_{3} …..



PV = nRT
P = Pressure (atmospheres)
V = Volume (liters)
n = # of moles
R = 0.0820 (L atm)/(mol K)
T = temperature in K


How many moles of H_{2} gas are there in 20 L at 4 atm and 400K? 

Use the Ideal Gas Law: PV = nRT
n = 2.44 moles



Standard temperature (0 C, 273 K) and standard pressure (1 atm or 760 torr) 

GayLussac’s Law of Combining Gas Volumes 

When only gases are involved in a reaction, the volumes of reactants and products are in a small, whole number ratio. 

Avagadro’s Law (for gases) 

Under the same conditions of temperature and pressure, equal volumes of gases contain equal numbers of moles. 

What is the volume of 1 mole of any gas at STP? 


N_{2} + 3H_{2} ↔2 NH_{3}
In the above reaction, how many L of NH_{3} will be produced from 6 L of H_{2}?


According to GayLussac’s Law, the volumes of gases are in direct proportion to the coefficients in the equation.
;
x = 4 L of ammonia

