2. An alkane has a relative molecular mass of 58, determine its molecular formula.

C4H10.

Explanation:

The general formula for an alkane is CnH (2n+2).

C = 12 and H = 1 (Molecular masses).

So we have the equation:

12n + 2n + 2 = 58

14n = 56

n = 4.

So the formula is

C4H (2*4+2)

= C4H10.

C4H10 Butane

Explanation:

(CnH2n+2) = 58

But the mass of C = 12 and H = 1

12n + 2n + 2 = 58

14n + 2 = 58

14n = 58 - 2

14n = 56

n = 56/14

n = 4

Hence the alkane is C4H10 i. e Butane