# Question #1cb83

##### 1 Answer

Here's what I got.

#### Explanation:

The trick here is to realize that under **STP conditions**, which are currently defined as a pressure of **mole** of any ideal gas occupies **molar volume of agas at STP**.

Now, you know that at STP, this gas has a **density** of

Use the molar volume of a gas at STP to find the number of moles present in the sample

#1 color(red)(cancel(color(black)("L"))) * "1 mole gas"/(22.723color(red)(cancel(color(black)("L")))) = "0.0440083 moles gas"#

To find the **molar mass** of the gas, you need to find the mass of exaftly **mole**. Since you know that **moles** have a mass of

#1 color(red)(cancel(color(black)("mole"))) * "1.7824 g"/(0.0440083color(red)(cancel(color(black)("moles")))) = "40.501 g"#

Therefore, you can say that the **molar mass** of the gas is equal to

#color(darkgreen)(ul(color(black)("molar mass = 40.501 g mol"^(-1))))#

The answer is rounded to five **sig figs**, the number of sig figs you have for the density of the gas at STP.

**SIDE NOTE** *More often than not, the molar volume of a gas at STP is given as #"22.414 mol L"^(-1)#, the value that corresponds to a pressure of*

*and a temperature of*

*If that's the value given to you, make sure to redo the calculations using* *instead of*