# Question #24fe2

##### 1 Answer

#### Explanation:

The idea here is that you need to use the ideal gas law to determine how many *moles* of gas you have in that sample.

Once you know how many moles you get in *molar mass*.

So, the ideal gas law equation looks like this

#PV = nRT" "# , where

*ideal gas constant*, equal to

Rearrange this equation to find the number of moles of gas you have in that sample under those specific conditions for pressure and temperature

#n = (PV)/(RT)#

#n = (1.30color(red)(cancel(color(black)("atm"))) * 825 * 10^-3color(red)(cancel(color(black)("L"))))/(0.082(color(red)(cancel(color(black)("atm"))) * color(red)(cancel(color(black)("L"))))/("mol" * color(red)(cancel(color(black)("K")))) * (273.15 + 19)color(red)(cancel(color(black)("K")))) = "0.04477 moles"#

The **molar mass** of a substance tells you what the mass of **one mole** of that substance is. In yur case, you have

#M_"M" = m/n#

#M_"M" = "0.742 g"/"0.04477 moles" = "16.57 g/mol"#

I'll leave the answer rounded to three sig figs

#M_"M" = color(green)("16.6 g/mol")#