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

Answer:

$r_{He}=169.7m/s$

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:

$\frac{r_{O_2}}{r_{He}} =\sqrt{\frac{M_{He}}{M_{O_2}} }$

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:

$r_{He}=r_{O_2}\sqrt{\frac{M_{He}}{M_{O_2}} }\\\\r_{He}=480m/s\sqrt{\frac{4.0g/mol}{32.0g/mol} }\\\\r_{He}=169.7m/s$

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