# Question #5f515

##### 1 Answer

#### Explanation:

What you need to do here is use the molar volume of a gas at STP to determine how many **moles** of gas you have in that *molar mass*.

**STP** conditions are defined for a pressure of **one mole** of any ideal gas occupies exactly

Convert the volume given to you from *milliliters* to *liters* first

#80 color(red)(cancel(color(black)("mL"))) * "1 L"/(1000color(red)(cancel(color(black)("mL")))) = "0.080 L"#

So, if **one mole** occupies

#0.080 color(red)(cancel(color(black)("L"))) * "1 mole"/(22.7 color(red)(cancel(color(black)("L")))) = "0.003524 moles"#

of gas in your *molar mass* is defined as the mass of **one mole** of a substance. This means that you gas will have a molar mass of

#M_M = "0.6 g"/"0.003524 moles" = "170.26 g/mol"#

You *should* round this off to one sig fig, the number of sig figs you have for your values, but I'll leave the answer rounded to two sig figs

#M_M = color(green)("170 g/mol")#