A sample of neon effuses from a container in 76 seconds. The same amount of an unknown noble gas

A sample of neon effuses from a container in 76 seconds. The...

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Key Concepts

Effusion

Effusion refers to the process in which gas molecules escape through a small hole into an area of lower pressure. The rate at which a gas effuses depends on the average speed of its molecules, which is in turn influenced by the gas’s temperature and molar mass.

Graham’s Law of Effusion

Graham’s law of effusion states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass. This relationship allows for the comparison of the speeds or effusion times of different gases under the same conditions to determine relative molar masses.

Molar Mass Determination

By applying Graham’s law, one can relate the effusion times or rates of two gases to calculate the unknown gas's molar mass. Specifically, if the time taken for effusion is known for both gases, the ratio of these times squared, multiplied by the known molar mass, gives the molar mass of the unknown gas.

Properties of Noble Gases

Noble gases are chemically inert elements with relatively low reactivity and specific characteristic molar masses. Their identifying properties and known molar masses make them useful for comparison in effusion experiments to identify an unknown sample.

Transcript

00:01 So in order to solve this equation, we need to know about graham's law of effusion.

00:12 And graham's law of affusion states that the rate of gas effusion is inversely proportional to the square root of their molar masses.

00:22 So the equation can be written as so, or the rate of one substance, substance a, over the rate of another substance, substance b, is equal to the square root of of the molar mass of b over the molar mass of a.

00:42 So we have time in our given units, so are you given values? so we need to convert rate to time.

00:52 But as we know, rate is inversely proportional to time.

01:01 So all we need to do is switch these around and we'll get time.

01:08 So rate would be one over the time of a, over 1 over the time of b is equal to mb over m a and then crossing these out we would get the t of b over the t of a is equal to the square root of the molar mass of b over the molar mass of a okay so without other the way, let's plug in our numbers.

01:46 So we know we have neon, and neon effuses at a rate of 76 seconds.

01:54 So that's our first substance.

01:56 So we're going to fill in neon for a here.

02:00 So that's 76 seconds.

02:03 And the rate of our unknown substance, or fuses at 150s, 5 seconds.

02:09 So we write 155 seconds.

02:15 So for molar masses, we do not know the molar mass...

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