Question

Which gas below has the largest number of moles at STP?

a.) 22.4L Ne
b.) 20L Ar
c.) 2.24L Xe
d.) They all have the same number of moles.
​

Answer 1

a.) 22.4 L Ne.

Step-by-step explanation:

It is known that every 1.0 mol of any gas occupies 22.4 L.

For the options:

• 22.4 L Ne:

It represents 1.0 mol of Ne.

• 20 L Ar:

using cross multiplication:

1.0 mol occupies → 22.4 L.

??? mol occupies → 20 L.

The no. of moles of (20 L) Ar = (1.0 mol)(20 L)/(22.4 L) = 0.8929 mol.

• 2.24 L Xe:

using cross multiplication:

1.0 mol occupies → 22.4 L.

??? mol occupies → 2.24 L.

The no. of moles of (2.24 L) Xe = (1.0 mol)(2.24 L)/(22.4 L) = 0.1 mol.

• So, the gas that has the largest number of moles at STP is: a.) 22.4 L Ne.