Question

At a certain temperature, O2 molecules move at an average velocity of 480 m/s. At that same temperature what would be the velocity of He atoms?

Answer 1

`r_(He)=169.7m/s`

Step-by-step explanation:

Hello there!

In this case, since this problem can be understood via the Graham's law, which states that states that the rate of diffusion or of effusion of a gas is inversely proportional to the square root of its molecular weight, which can be extrapolated to the rate, we have:

`(r_(O_2))/(r_(He)) =\sqrt{(M_(He))/(M_(O_2)) }`

Thus, since the molar mass of helium is 4.0 g/mol and that of oxygen is 16.0 g/mol, we solve for the average velocity of helium as shown below:

`r_(He)=r_(O_2)\sqrt{(M_(He))/(M_(O_2)) }\\\\r_(He)=480m/s\sqrt{(4.0g/mol)/(32.0g/mol) }\\\\r_(He)=169.7m/s`

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