Question

a chemist isolated a gas in a glass bulb with a volume of 255 ml at a temperature of 25 and a pressure of 10 torr. The gas weighed 12.1 mg. What is the molecular mass of this gas

Answer 1

Answer:

88.5 g/m is the molar mass for the gas

Explanation:

We need the Ideal Gases Law equation to solve this:

P . V = n . R . T

Pressure (P) = 10 Torr

We must convert to atm → 10 Torr / 760 Torr = 0.0131 atm

Volume (V) = 255 mL

We must convert to L → 255 mL /  1000 = 0.255 L

n = number of moles

moles = mass in g / molar mass

12.1 mg/ 1000 = 0.0121 g

T° = 25°C + 273K = 298K

R = 0.082 L.atm /mol.K

Let's replace the values

0.0131 atm . 0.255L = 0.0121 g / x .  0.082 L.atm /mol.K  . 298K

(0.0131 atm . 0.255L) / (0.082 L.atm /mol.K  . 298K) = 0.0121 g / x

1.367×10⁻⁴ /mol = 0.0121 g / x

x = 0.0121 g / 1.367×10⁻⁴ mol = 88.5 g/m