Gas Unit 3/5
The student will Learn:
1. calculation of gas problems
using the Ideal Gas Law.
PV = nRT
Ideal Gas Law
Involves P,V,T & …number of moles of gas
PV = nRT
All units must be :
P = atm
V = liters
T = Kelvin
n = #of moles
R = .0821
liters x atm
moles x K
R is a constant …….. Like pi is a constant 3.14
ws.11.21
3 Options for R gas constant
0.0821
L x atm
mol x K
8.315
L x Kpa
mol x K
62.4
L x mmHg
mol x K
Ws. 11.21
1. If 6 moles of CO2 gas is contained at a pressure of
7.6 atm and a volume of 20 liters, calculate the
temperature of the gas. Answer in Celsius degree.
2. A 31 liter tank contains a gas at 12.2 atm with a
temperature of 273k. What is the weight in grams of
the dinitrogen oxide, laughing gas, inside the tank?
3. What is the volume of a balloon if it contains 19.2
moles of helium, an internal pressure 770mmHg and
the outside temperature is 80oC?
4. If I have an unknown quantity of gas at a temperature
80oC, and a volume of 25 liters and the tank pressure
registers at 2000mmHg. How many moles of the
unknown Gas?
5. A one liter aerosol can of WD-40 at room
temperature (25oC) is thrown into an incinerator.
Calculate the temperature of the gas in the can with an
internal pressure of 3atms and 0.05 moles of WD-40
were in the can? Assume the can did not explode.
ws.11.21
How do I know when to use the
Combine Gas Law or the Ideal Gas law?
Gas Unit 3/5
The student will Learn:
1. calculation of gas problems
using the Ideal Gas Law.
PV = nRT
Gas Unit 4/5
The student will learn:
1. concept of Dalton’s Law of Partial Pressure.
2. calculations of Dalton’s law of Partial Pressure.
Dalton’s Law of Partial Pressure
Total pressure of a mixture of gases =
sum of partial pressure of the component gases.
Ptotal = P1 + P2 + P3 + P4 …
1.
If 5 gases in a cylinder each exert 1atm, what is the total
pressure exerted by the gases?
2. Three samples of gas each exert 740mm Hg in separate
2-L tanks. What pressure do they exert if they are all
placed in a single 2-L tank.
3. A mixture of four gases exerts a total pressure of 860
mmHg. Gases A and B each exert 220 mmHg. Gas C
exerts 110mmHg. What pressure is exerted by gas D?
Gas Unit 4/5
The student will learn:
1. concept of Dalton’s Law of Partial Pressure.
2. calculations of Dalton’s law of Partial Pressure.
Gas Unit
5/5
The student will learn:
1. concept of rate of diffusion
2. minor calculations in rate of diffusion.
Diffusion
KMT: 4- No significant forces of attraction or repulsion
between gas particles
So…..gas particles can flow easily
past one another
3- Gas particles are in constant, rapid, random
motion. They have KE.
So….. motion of gas particles
causes the gas particles to evenly mix.
Diffusion =movement of one material through another material.
“Cooking cookies in the kitchen…others
can
smell it upstairs in the bedroom.”
Rate of Diffusion depends on mass
---Skinny people can run faster than fat people-----So can molecules---
Lighter molecule diffuse faster than heavy molecules @ STP
Of the following molecules which would diffuse faster?
l.
Oxygen or Neon
2
Sulfur dioxide or carbon dioxide
3.
Chlorine gas or krypton gas
List the following gases in order of
increasing rate of diffusion.
(a) He
(b) Xe
(c) HCl
(d)Cl2
The two gases in the figure below are simultaneously
injected into opposite ends of the tube. They should just
begin to mix at which labeled point?
H2S
SO2
A
B
C
How does the diffusion rate of hydrogen molecules
compare with that of oxygen molecules when both
gases are at 250C
1.
2.
3.
4.
5.
They have equal rates
Hydrogen is 1/16 as fast
as oxygen
Hydrogen is 16 times
faster than oxygen
Hydrogen is 4 times as
fast
More information is
needed
Gas Unit
5/5
The student will learn:
1. concept of rate of diffusion
2. minor calculations in rate of diffusion.