Question 1

Acetone (CH3) 2CO is a volatile Liquid that can be readily converted to vapour.

Calculate the density of acetone vapour at 100,000 Pa and 398 K in kg/m3. Assume

ideal behaviour and use R=8.314 J/mol. K.

Your Answer:

Answer

1.76 kg/m³

Explanation:

1) dа ta:

a) Chemical formula: (CH₃) ₂CO

b) P = 100,000 Pa

c) T = 398 K

d) D = ?

e) R = 8.314 J / mol. K

2) Principles and formulae:

a) Ideal behaviour of a gas means that it follows the ideal gas equation:

PV = nRT

b) Density, D = mass / volume

c) mass in grams = n * molar mass

3) Solution:

a) Transform the ideal gas equation to solve for the density:

PV = nRT (n = mass in grass / molar mass)

PV = (mass in grams / molar mass) RT

(mass in grams / V) = P * molar mass / (RT)

mass in kg * 1,000 (g / kg) / V = P * molar mass / (RT)

(mass in kg / V) = P * molar mass / (1,000RT)

D = P * molar mass / (1,000RT)

b) Molar mass of (CH₃) ₂CO: 58.08 g/mol

c) Substitute and compute:

D = 100,000 Pa * 58.08 kg/mol / (1,000 * 8.314 J/mol. K * 398 K)

* (note that by dividing by 1,000 the molar mass is transformed from g/mol to kg/mol)

D = 1.76 kg/m³← answer