Question

A flask with a volume of 3.16 l contains 9.33 grams of an unknown gas at 32.0°c and 1.00 atm. What is the molar mass of the gas?

Answer 1

73.88 g/mol

Step-by-step explanation:

For this question we have to keep in mind that the unknown substance is a gas, therefore we can use the ideal gas law:

`PV=nRT`

In this case we will have:

P= 1 atm

V= 3.16 L

T = 32 ªC = 305.15 ºK

R= 0.082
`(atm*L)/(mol*K)`

n= ?

So, we can solve for "n" (moles):

`1~atm*3.16~L~=~n*0.082~(atm*L)/(mol*K)*305.15~K`

`n=(1~atm*3.16~L~)/(0.082~(atm*L)/(mol*K)*305.15~K)`

`n=0.126~mol`

Now, we have to remember that the molar mass value has "g/mol" units. We already have the grams (9.33 g), so we have to divide by the moles:

`molar~mass=(9.33~grams)/(0.126~mol)`

`molar~mass=73.88(grams)/(mol)`