Question

10. A sample of gas occupies 4.00 L at 80.0 kPa at 303 K. How many moles of gas are in the sample? If the sample weighs 20.50 grams, what is its molar mass of the gas?​

Answer 1

Moles:
`n=0.127mol`

Molar mass:
`M=200.61 g/mol`

Step-by-step explanation:

Hello,

In this case, we can use the ideal gas equation to compute the moles of the gas sample as shown below:

`PV=nRT\\\\n=(PV)/(RT)`

Thus, we should use the pressure in atm as follows:

`n=(80.0kPa*(0.00986923atm)/(1kPa)*4.00L)/(0.082(atm*L)/(mol*K)*303K)\\ \\n=0.127mol`

Moreover, the molar mass is obtained by dividing the given mass by the obtained moles:

`M=(m)/(n)=(25.50g)/(0.127mol)\\ \\M=200.61 g/mol`

Best regards.