# Chem geniuses, i need some help

Discussion in 'Pre-Medical - MD' started by WorkOnIt, Nov 15, 2002.

1. ### WorkOnIt Junior Member 7+ Year Member

Joined:
Nov 15, 2002
Messages:
20
0
! I need some help from my fellow chem geniuses. This is the prob. that has me stuck:

The effusion rate of an unknown gas is measured and found to be 31.50 mL/min. Under identical expermential conditions, the effusion rate of O2(oxygen) is found to 30.50 mL/min. If the choices are CH4, CO, NO, CO2, and NO2, what is the indentity of the unknown gas?

My book says the answer is NO. but i dont see how the answer is obtain. what steps and equation are used???

2. ### BrainDrain Member 7+ Year Member

Joined:
May 13, 2002
Messages:
98
0
just plug into formula:

Effusion Rate O2/Effusion Rate X=square root(Mol.W X/MW O2)

squared(30.5/31.5)=Mol.W X/32

Mol.W X=30

which is the Mol. Wt. of NO

Hope you can understand this

3. OP

### WorkOnIt Junior Member 7+ Year Member

Joined:
Nov 15, 2002
Messages:
20
0
thanks for reply. it took me a min., but i got it. but just to be sure , this is how u would do it, right:

squared(30.5/31.5)=Mol.W X/32

976= 31 Mol. W X

976/31.5=30.9 but i guess u can take NO since its the nearest 30. if thats how u do it, sorry but i'm just a bit of a perfectonist

4. ### BrainDrain Member 7+ Year Member

Joined:
May 13, 2002
Messages:
98
0

squared(30.5/31.5)=Mol.W X/32

squared(0.968)=Mol.W X/32

0.9375 X 32=Mol.W

Mol. W=30.00

5. OP

### WorkOnIt Junior Member 7+ Year Member

Joined:
Nov 15, 2002
Messages:
20
0
oh, i see. thanks

We’ve been on the Internet for over 20 years doing just one thing: providing career information for free or at cost. We do this because we believe that the health education process is too expensive and too competitive.

We believe that all students deserve the same access to high quality information. We believe that providing high quality career advice and information ensures that everyone, regardless of income or privilege, has a chance to achieve their dream of being a doctor.