# What would be the volume of a 13.70 g sample of the noble gas krypton at STP?

##### 1 Answer

The volume occupied by the gas will be

When you are given **STP** conditions, which imply a pressure of **100 kPa** and a temperature of **-273.15 K**, you must think molar volume of a gas.

At **STP**, 1 mole *of any ideal gas* occupies exactly **22.7 L**. This means that, in order to get the volume of a gas at STP, all you need to do is figure out how many moles of the gas you're dealing with.

Use krypton's molar mass to determine how many moles you have in **13.70 g**

So, if 1 mole occupies 22.7 L, fewer moles will of course occupy a smaller volume.

**SIDE NOTE** *You'll very often see the molar volume of a gas at STP being given as 22.4 L - that's the (very) old value used for STP conditions defined as 1 atm and 0 degrees Celsius*.

*I suggest using 22.7 L, the actual value, unless your teacher instructs you to use 22.4 L.*