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Standard Temperature and Pressure
Effusion
Root Mean Square Speed
Kinetic Energy of Gases
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Van der Waals Equation
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Manometer
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LearnAdditional PracticeSummary
Next SectionRoot Mean Square Speed

Effusion is the escaping of gas molecules or atoms through a pinhole. 

Effusion

Concept #2: Rate of Effusion

Example #1: Rank the following in order of increasing rate of effusion.

O2           PF5           CO2           Xe

Concept #3: Graham’s Law of Effusion

Example #2: Calculate the ratio of the effusion rates of helium to methane (CH4).

Practice: If H2 has an effusion rate that is 3.72 times faster than a gas, what is the identity of the unknown gas?

Practice: How many times faster will H2 gas pass through a pinhole into an area of vacuum than O2 gas?

Practice: It takes 6.3 minutes for 2.3 L argon to effuse through a semipermeable membrane. How long would it take for 2.3 L of chlorine gas to effuse under similar conditions?

Previous SectionStandard Temperature and Pressure
Next SectionRoot Mean Square Speed
Additional Problems
Exactly 10 mL, of gas A (MM = 15.0 g/mol) effuse through an opening in 2.0 sec. Exactly 10 mL of gas B effuse through the same opening in 8.0 sec. What is the molar mass of gas B? a) 60 g/mol b) 480 g/mol c) 240 g/mol d) 120 g/mol
A sample of N2 gas is contaminated with a gas (A) of unknown molar mass. The partial pressure of each gas is known to be 200 Torr at 25°C. The gases are allowed to effuse through a pinhole, and it is found that gas A escapes at three times the rate of N2. The molar mass of gas A is: a) 3.11 b) 252 c) 84.0 d) 9.33 e) none of these 
The mass of particle A is 10% larger than that of particle B. If particle B travels 100m during effusion, how far would particle A travel during effusion? a. 90 m b. 95 m c. 100 m d. 105 m e. 110 m
A sample of helium effuses through a porous container 7.70 times faster than does unknown gas X. What is the molar mass of the unknown gas? 1. 129.96 2. 153.76 3. 169.0 4. 112.36 5. 190.44 6. 237.16 7. 275.56 8. 392.04 9. 201.64 10. 368.64
At any given temperature, how much more quickly will He effuse than Xe? 1. 5.7 times more quickly 2. .03 times more quickly 3. 8.1 times more quickly 4. They will diffuse at the same rate 5. 0.12 times more quickly 6. 32.8 times more quickly
Carbon dioxide effuses through a pinhole at a rate of 0.232 ml/min at 25.0 °C. Another gas effuses at a rate of 0.363 ml/min. What is the molar mass of the gas?
How many times faster will He gas pass through a pin hole than SO2 gas? a) 4 b) 1/4 c) 16 d) 1/16 e) none of the given answers
The mass particle is 10% larger than that of particle B. If particle B travels 100 m during effusion, how far would particle A travel during effusion? a) 90 m  b) 95 m c) 100 m  d) 105 m e) 110 m 
Consider the chemical reaction: 2 SO2 (g) → SO(g) + SO3 (g) Determine if the sentence below is true or false Between the two products, SO3 would have the highest rate of effusion.
NO2 gas effuses ________times faster than Cl 2 gas. a. 1.54 b. 0.649 c. 1.24 d. 0.770 e. 2.37
The rate of effusion of oxygen to an unknown gas is 0.935. What is the other gas? A) Ar B) F2 C) Ne D) N2
Oxygen gas effuses at a rate that is 1.49 times that of an unknown gas (at the same temperature).  What is the identity of the unknown gas? A) Ar                     B) HBr            C) SO2             D) Cl2              E) He
Second-hand smoke consist of many molecules including nicotine. How much faster or slower does the nicotine diffuse, compared to carbon dioxide? (MW nicotine = 160g/mol) 1. About half as fast 2. As gases, the two molecules diffuse at the same rate 3. About 4 times faster 4. About a fourth as fast 5. About twice as fast
The gas for which instance will effuse faster?
At a given temperature and pressure, a sample of Gas A is observed to diffuse twice as fast as a sample of a different gas, B. Based on this: A. The molar mass of A is one fourth that of B B. The molar mass of A is one half that of B C. The molar mass of A is 0.707 times that of B D. The molar mass of A is 1.414 times that of B E. The molar mass of A is four times that of B
An unknown gas Q diffuses at a RATE 1.65 times faster than that of propane, C 3H8. Which of these are most likely to be Q? a. He b. Ne c. H2O d. CH4 e. O2
Using Graham's Law of effusion, calculate the ratio of the effusion rates of H 2 to CO through a pinhole.
Which gas has molecules with the greatest average molecular speed at 25°C?A) ArB) N2C) CO2D) CH4 E) Kr
Which gas is the predominant nitrogen-containing pollutant in the atmosphere?a) NH3b) N2c) N2O5d) NO2 
Consider a 1.0-L sample of helium gas and a 1.0-L sample of argon gas, both at room temperature and atmospheric pressure. d. Which gas sample would have the faster rate of effusion? 
A flask at room temperature contains exactly equal amounts (in moles) of nitrogen and xenon.d. If a small hole were opened in the flask, which gas would effuse more quickly? 
Calculate the ratio of effusion rates for Ar and Kr. 
A sample of neon effuses from a container in 76 seconds. The same amount of an unknown noble gas requires 155 seconds. Identify the gas. 
A sample of N2O effuses from a container in 42 seconds. How long would it take the same amount of gaseous I2 to effuse from the same container under identical conditions? 
The rate of effusion of two different gases is known asA) Avogadro's Law   B) Graham's Law       C) Charles's Law        D) Boyle's LawE) Dalton's Law
Given the gases Ne, He, H2, Kr, put them in order of their INCREASING rate of effusion. 1. Kr < Ne < He < H 2 2. H2 < He < Ne < Kr 3. He < H2 < Kr < Ne 4. Ne < Kr < H 2 < He
Rank from the highest to lowest effusion rate. To rank items as equivalent, overlap them.H2, Ar, Ne, C4H8, CO
Calculate the ratio of effusion rates of Cl2 to F2.
One way of separating oxygen isotopes is by gaseous diffusion of carbon monoxide. The gaseous diffusion process behaves like an effusion process. Calculate the relative rates of effusion of 12C16O, 12C17O, and 12C18O. Name some advantages and disadvantages of separating oxygen isotopes by gaseous diffusion of carbon dioxide instead of carbon monoxide.
Find the ratio of effusion rates of hydrogen gas and krypton gas.
If 250 mL of methane, CH4, effuses through a small hole in 28 s, the time required for the same volume of helium to pass through the hole under the same conditions will be 
The rate of effusion of oxygen to an unknown gas is 0.935. What is the other gas?
How much faster do ammonia (NH 3) molecules effuse than carbon monoxide (CO) molecules?Enter the ratio of the rates of effusion. Express your answer numerically using three significant figures. 
Calculate the ratio of effusion rates for Ar and Kr.