# Problem: Of these gases, which has the fastest-moving molecules (on average) at a given temperature?a. HBrb. NO2c. C2H6d. they all have the same average speed

###### FREE Expert Solution

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

µrms = rms speed,
R = 8.314 J/(mol·K) → constant
T = temperature, K → constant
M = molar mass, kg/mol

Compare molar masses

###### Problem Details

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

a. HBr

b. NO2

c. C2H6

d. they all have the same average speed