Question

A sample of Xe takes 75 seconds to effuse out of a container. An unknown gas takes 37 seconds to effuse out of the identical container under identical conditions. What is the most likely identity of the unknown gas?
a. Br2
b. He
c. O2
d. Kr

Answer 1

Answer:

The Answer is (c)

Explanation:

Answer 2

Answer:

The molar mass of B is 32.0 g/mol

The unknown gas might be O2 (option C)

Explanation:

Step 1: Data given

A sample of Xe takes 75 seconds to effuse out of a container.

An unknown gas takes 37 seconds to effuse out of the identical container

Molar mass Xe = 131.3 g/mol

Step 2:

Rate A / rate B = √ (MB/MA)

rate = amount / time

The equation includes rate, but you are given times. Since rate is amount/time, we have to invert that side of the equation.

Time B/Time A = √(MB/MA)

⇒with time B = the time the unknown gas needed to effuse  = 37 seconds

⇒with time A = the time needed Xe needed to effuse = 75 seconds

⇒with MB = the molar mass of the unknown gas = TO BE DETERMINED

⇒ with MA = the molar mass of Xe = 131.3

37/75 = √ (MB/131.3)

MB = 32

The molar mass of B is 32.0 g/mol

The unknown gas might be O2