A mixture of CO2 and an unknown gas was allowed to effuse from a container. The carbon dioxide took 1.25 times longer than the unknown gas to escape.Which of the following gases could the unknown one be

Choices
A: Cl2
B: CO
C: HCl
D: H2
E: SO2

I am going B
for this reason:
CO2 is 44.01
CO is 28.0102
so that means that CO is 1.25 times lighter...??
Is this correct??
So that means B is correct ???
Thanks
Andy

I agree although I solved the problem mathematically. I don't know how you used 1.25 and 44 to arrive at 28.

The ratio is to the square root of the molar masses so 44/(1.25^2 = 28 but 44/1.25 = 35

Yes, your reasoning is correct. The unknown gas must be lighter than CO2 since it took 1.25 times less time to escape. Comparing the molar masses, CO2 (44.01 g/mol) is heavier than CO (28.0102 g/mol), so it's likely that the unknown gas is CO. Therefore, your choice of B is correct.

To determine which gas could be the unknown one, we need to compare their molar masses and relate them to the effusion times.

The rate of effusion of a gas is inversely proportional to the square root of its molar mass.

Let's compare the molar masses of CO2, CO, and the unknown gas:

Molar mass of CO2 = 44.01 g/mol
Molar mass of CO = 28.0102 g/mol

If the effusion times of CO2 and the unknown gas are in a 1.25:1 ratio, that means the square root of the ratio of their molar masses should also be 1.25.

Using this information, we can calculate the molar mass of the unknown gas:

(Molar mass of CO2) / (Molar mass of the unknown gas) = (1.25)^2

(44.01 g/mol) / (Molar mass of the unknown gas) = 1.5625

Solving for the molar mass of the unknown gas, we get:

Molar mass of the unknown gas = 44.01 g/mol / 1.5625 ≈ 28.09 g/mol

Comparing this molar mass to the options given, we can see that the molar mass of the unknown gas is very close to that of CO (28.0102 g/mol). Therefore, the unknown gas is most likely CO.

Therefore, the correct choice is B: CO.

Great job for coming to the correct conclusion!