A mixture of neon gas and argon gas is present in a container (container A). There are equal amounts of both gases in the container. A small pinhole is created in the container, allowing the gases to effuse into an empty container (container B). The effusion time is very brief, and the pinhole is eventually plugged, resulting in a mixture of both gases in both containers.

You are watching: Which of the following gases effuses most rapidly?


Correct answer:

The partial pressure for argon is greater than the partial pressure for neon in container A


Explanation:

The rate of effusion for two gases can be compared to one another using the following equation:

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Here, the effusion rates are inversely proportional to the square root of the molecular masses of the gases in question. Because the relationship is to the square roots of the molecular masses, we will not observe a 2:1 ratio of effusion for neon compared to argon.

We will, however, see that more neon effuses out of container A compared to the amount of argon because neon is the lighter gas and will thus have a faster effusion rate. As a result, there will be more argon than neon in container A after the pinhole is plugged. This results in argon having a larger partial pressure than neon in container A.


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Example Question #2 : Effusion


A glass box holds equal amounts of hydrogen, nitrogen, oxygen, and bromine. The gases are allowed to exit the container through a tiny hole. Which gas will exit the hole the fastest?


Possible Answers:

Hydrogen


Oxygen


Nitrogen


Bromine


They all exit at the same rate because the temperature is constant


Correct answer:

Hydrogen


Explanation:

At a particular temperature, the average kinetic energy of all gaseous molecules is equal. Since hydrogen gas has the lowest mass out of these gases, it will have the highest average velocity. This means that it will exit out of the tiny hole at a rate faster than the other gases. Conversely, bromine, which has the most mass compared to the other gases, will exit the hole the slowest.

This relationship is mathematically represented in Graham"s law:

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As the mass increases, the rate of effusion decreases.


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Example Question #3 : Effusion


Which of the following gases will have the highest rate of effusion?


Possible Answers:

Carbon dioxide


Oxygen


Helium


Sulfur dioxide


Nitrogen


Correct answer:

Helium


Explanation:

The rate of effusion for a gas is inversely proportional to the square-root of its molecular mass (Graham"s Law).

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The gas with the lowest molecular weight will effuse the fastest.

Oxygen:

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Nitrogen:

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Carbon dioxide:

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Sulfur dioxide:

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Helium:

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The lightest, and therefore fastest, gas is helium.


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Example Question #4 : Effusion


Molecule A has twice the mass of molecule B. A sample of each molecule is released into separate, identical containers. Which compound will have a higher rate of diffusion?


Possible Answers:

Molecule A would have a faster initial rate; both molecules would reach an equal final rate


Molecule B


Molecule A


They will have identical rates of diffusion


There is not enough information to determine relative rates of diffusion


Correct answer:

Molecule B


Explanation:

According to Graham"s law, the rate of diffusion of a gas molecule is inversely proportional to the root square of that molecule"s mass. Because molecule B has a smaller mass than molecule A, it will have a higher rate of diffusion.

 

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Correct answer:


Explanation:

We can compare the effusion rates of these gases using the following equation.

 

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By calling neon "gas 1" and argon "gas 2," we can compare the effusion rates of the two gases by plugging their molecular masses into the equation.

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This proportion is equal to the rate of neon effusion over the rate of argon effusion, giving the ratio of neon atoms to argon atoms in container B.

See more: Which Is Greater A Quart Or A Pint, Us Standard Volume

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As a result, 141 atoms of neon gas will effuse out of the pinhole for every 100 argon gas atoms. Keep in mind that the heavier gas will effuse at a slower rate than the lighter gas; thus, we would expect there to be more neon than argon in container B.



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Let us assume that the two compounds form a precipitate in the tube 6cm to the left of the right cotton ball. What is the molar mass of the mystery compound?