The number of hydrogen atoms in an alkane molecule with a relative molecular weight of 100 is

Alkanes are organic compounds made up of carbon and hydrogen. Alkanes – refer to saturated hydrocarbons, in the molecules of which carbon is in the state of sp3 – hybridization.

All alkanes obey the general formula Cn H2n + 2. When solving this problem, we use the general formula of alkanes.

Given: Mr (alkane) = 100

Alkane formula -?

Decision.

Let’s calculate the relative molecular weight of the alkane in general form – СnH2n + 2.

Мr (С) = 12, Мr (Н) = 1, hence Мr (СnH2n + 2) = 12 * n + 1 * (2n + 2)

Mr (CnH2n + 2) = 12n + 2n + 2; Мr (СnH2n + 2) = 14n + 2

Since Мr (СnH2n + 2) is equal to 100 according to the problem statement, we compose the equation:

14n + 2 = 100

14n = 100 – 2

14n = 98

n = 98/14

n = 7, therefore, in an alkane molecule there are 7 carbon atoms and hydrogen atoms: 2 * 7 + 2 = 16

Hence: the formula for the alkane is C7 H16. Its name is heptane.

Answer: C7 H16 – heptane.