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

Answer:

Moles: $n=0.127mol$

Molar mass: $M=200.61 g/mol$

Explanation:

Hello,

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

$PV=nRT\\\\n=\frac{PV}{RT}$

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

$n=\frac{80.0kPa*\frac{0.00986923atm}{1kPa}*4.00L}{0.082\frac{atm*L}{mol*K}*303K}\\ \\n=0.127mol$

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

$M=\frac{m}{n}=\frac{25.50g}{0.127mol}\\ \\M=200.61 g/mol$

Best regards.