Determine the formula for the limiting hydrocarbon Mr = 72.

Saturated hydrocarbons have a general gross formula of the type CnH (2n + 2). From the problem statement, we know that the relative molar mass of the compound is 72 g / mol.

The relative molar mass is found as the sum of the relative masses of the carbon and hydrogen atoms that make up the compound. In general, it looks like this:

M = 12 * n + 1 * (2n + 2)

Because we know the molar mass, we get an equation with one variable:

12 * n + 1 * (2n + 2) = 72

12n + 2n + 2 = 72

14n = 72 – 2

14n = 70

n = 70: 14

n = 5

Substituting the value of the variable n into the general formula, we get C5H12. This formula corresponds to the hydrocarbon pentane.

Answer: C5H12 pentane