Question 5

Determine the mass (in g) of oxygen (Mc = 32.00) that occupies a volume of 146.7 cm? at a pressure of

106.5 kPa and a temperature of 167 °C. Give the answer to 3 significant figures

9

0.128 g

Explanation:

Given dа ta:

Volume of gas = 146.7 cm³

Pressure of gas = 106.5 Kpa

Temperature of gas = 167°C

Mass of oxygen gas = ?

Solution:

Volume of gas = 146.7 cm³ (146.7 / 1000 = 0.1467 L)

Pressure of gas = 106.5 Kpa (106.5/101 = 1.1 atm)

Temperature of gas = 167°C (167 + 273.15 = 440.15 K)

PV = nRT

P = Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm. L / mol. K

T = temperature in kelvin

n = PV/RT

n = 1.1 atm * 0.1467 L / 0.0821 atm. L / mol. K * 440.15 K

n = 0.1614 / 36.14 / mol

n = 0.004 mol

Mass of oxygen:

Mass = number of moles * molar mass

Mass = 0.004 mol * 32 g/mol

Mass = 0.128 g