Question

Determine the molecular formula for the following hydrocarbons: a. Hexane b. Methane c. Propyne d. 1-pentene e. 2-octyne f. Decane g. Heptane h. 4-nonene

Answer 1

Answer: The molecular formulas are written below.

Step-by-step explanation:

Saturated hydrocarbons are defined as the hydrocarbons in which a single bond is present between carbon and carbon atoms. The general formula for these hydrocarbons is
`C_nH_(2n+2)`

These hydrocarbons have the name ending with the suffix '-ane'

Unsaturated hydrocarbons are defined as the hydrocarbons which have double or triple covalent C-C bonds. They are known as alkenes and alkynes respectively. The general formula for these hydrocarbons is
`C_nH_(2n)` and
`C_nH_(2n-2)`

The hydrocarbons having double and triple bonds have the name ending with the suffix '-ene' and '-yne' respectively.

For the given options:

Option a: Hexane

'Hex' prefix is added for the chain having 6-Carbon atoms. So, the formula for this saturated hydrocarbon is
`C_6H_((2* 6)+2)=C_6H_(14)`

Option b: Methane

'Meth' prefix is added for the chain having 1-Carbon atom. So, the formula for this saturated hydrocarbon is
`C_1H_((2* 1)+2)=CH_(4)`

Option c: Propyne

'Prop' prefix is added for the chain having 3-Carbon atoms. So, the formula for this unsaturated hydrocarbon is
`C_3H_((2* 3)-2)=C_3H_4`

Option d: 1-pentene

'Pent' prefix is added for the chain having 5-Carbon atoms. So, the formula for this unsaturated hydrocarbon is
`C_5H_((2* 5))=C_5H_(10)`. The double bond is present between C-1 and C-2 atoms

Option e: Octyne

'Oct' prefix is added for the chain having 8-Carbon atoms. So, the formula for this unsaturated hydrocarbon is
`C_8H_((2* 8)-2)=C_8H_(14)`

Option f: Decane

'Dec' prefix is added for the chain having 10-Carbon atoms. So, the formula for this saturated hydrocarbon is
`C_(10)H_((2* 10)+2)=C_(10)H_(22)`

Option g: Heptane

'Hept' prefix is added for the chain having 7-Carbon atoms. So, the formula for this saturated hydrocarbon is
`C_7H_((2* 7)+2)=C_7H_(16)`

Option h: 4-nonene

'Nona' prefix is added for the chain having 9-Carbon atoms. So, the formula for this unsaturated hydrocarbon is
`C_9H_((2* 9))=C_9H_(18)`. The double bond is present between C-4 and C-5 atoms