Chad Test Question

[hoylematt]

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Which of the following gases will have the lowest velocity at 150 degrees celcius?

a. Co2
b. CH4
c. Ar
d. Cl2

The explanation says that if all of them are at the same temp then they have the same kinetic energy--i understand that.

The second part comes from velocity physics:
Since K.E. = 1/2mv^2, the gas with the smallest mass (m) will have the highest velocity (v).

Am I smoking something? Doesnt CH4 have the smallest mass?
Co2 = 46amu
CH4 = 16amu
Ar = 40amu
Cl2 = 70amu

The answer is Cl2, please tell me why?

 

[CANgnome]

i think you read the question backwards 🙂

 

[duodenum]

V= squareroot(2 KE/m)....larger the mass, the lower the velocity...just remember that in any case, the larger the MW weight, the lower the velocity.

 

[chitah831]

V= squareroot(2 KE/m)....larger the mass, the lower the velocity...just remember that in any case, the larger the MW weight, the lower the velocity.

Yeah you read it incorrectly. Lightest = fastest (higher velocity). Heaviest = slowest (lower velocity) 🙂

 

[hoylematt]

I love how the reason i get it wrong is a stupid error. I need to read the stupid question better. Sorry guys.