# Question #bf746

##### 1 Answer

#### Explanation:

The idea here is that you can use the **molar volume of a gas at STP** to calculate the density of your sample of neon under these conditions.

More often than not, you'll find **STP** conditions defined as a pressure of **mole** of any ideal gas occupies

Now, in order to find the **density** of the gas, you must determine two things

themassof the samplethevolumeit occupies

Since you already know the volume, all you have to do here is to use the **molar mass** of neon to convert the number of moles in your sample to *grams*.

You will have

#1.0 color(red)(cancel(color(black)("moles Ne"))) * "20.18 g"/(1color(red)(cancel(color(black)("mole Ne")))) = "20.18 g"#

The density of the gas is defined as the mass of **exactly #1# unit of volume**. In your case, this means the mass of

Since you know that

#1 color(red)(cancel(color(black)("L"))) * "20.18 g"/(22.4color(red)(cancel(color(black)("L")))) = "0.90 g"#

Therefore, the density of **mole** of neon under STP conditions is

#color(darkgreen)(ul(color(black)("density = 0.90 g L"^(-1))))#

The answer is rounded to two **sig figs**, the number of sig figs you have for the sample of neon.