The density of the hydrocarbon in part (a) is 2.0 g l-1 at 50°c and 0.948atm. (i) calculate the molar mass of the hydrocarbon. (ii) determine the molecular formula of the hydrocarbon.

1. Answer;

=56 g/mol

Explanation and solution;

PV = nRT

nRT = mass/molar mass (RT)

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

= Density * (RT/P)

Molar mass = 2.0 g/L * (0.0821 * 323 K) / 0.948 atm

Molar mass = 56 g/mol

2. Answer;

Molecular mass is C4H8

Explanation;

Empirical mass * n = molar mass

Empirical mass for CH2 = 14 g/mol

Therefore;

56 g/mol = 14 g/mol * n

n = 4

The molecular formula = 4 (CH2)

= C4H8