${\mathbf{\mu}}_{\mathbf{rms}}\mathbf{=}\sqrt{\frac{\mathbf{3}\mathbf{RT}}{\mathbf{M}}}$

µrms = rms speed,

R = 8.314 J/(mol·K) **→ constant**

T = temperature, K **→ constant**

M = molar mass, kg/mol

**Compare molar masses **

${\mathbf{\text{\u2191}}}\mathbf{}{\mathbf{\mu}}_{\mathbf{rms}}\mathbf{=}\sqrt{\frac{\mathbf{3}\mathbf{RT}}{{\mathbf{\text{\u2193}}}\mathbf{}\mathbf{M}}}$

Of these gases, which has the fastest-moving molecules (on average) at a given temperature?

a. HBr

b. NO_{2}

c. C_{2}H_{6}

d. they all have the same average speed

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Root Mean Square Speed concept. You can view video lessons to learn Root Mean Square Speed. Or if you need more Root Mean Square Speed practice, you can also practice Root Mean Square Speed practice problems.

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Based on our data, we think this problem is relevant for Professor Odeleye's class at OU.