(a) Place the following gases in order of increasing average molecular speed at 300. K: CO, SF6, H2S, Cl2, HBr. (Use the appropriate <, =, or > symbol to separate substances in the list.)

 

So, I know how to do (a):

 

SF6 < HBr < Cl2 < H2S < CO

 

SF6 being the slowest and CO being the fastest.

 

(b) Calculate and compare the rms speeds of CO and Cl2 at 300. K.

 

rms speed of CO in m/s

 

rms speed of Cl2 in m/s

 

I have no idea how to do (b). Someone give me a start please?

 

Thanks!

the formula you're looking for is under "kinetic molecular theory of gases" in your textbook. it's something to do with the rms speed being equal to the square root of (3 times the gas constant times the temperature divided by M)... I think... something like that... look it up.