Question

What is the value of n in CH3(CH2)nCH3 if the name of the hydrocarbon is heptane

Answer 1

n+5 so the correct answer is b) 5

Step-by-step explanation:

just did review on edge

Answer 2

n = 5.

Step-by-step explanation:

How many carbon atoms in total in this straight-chain hydrocarbon?

The prefix of the IUPAC name of a hydrocarbon (the part before -ane) shows the number of carbon atoms on the longest carbon chain.

`\begin{array}c\text{Number of Carbon}\\ \text{atoms in backbone} & \text{Prefix}\\[-0.5em]\multicolumn{2}{c}{\rule{5cm}{0.5pt}}\\1& \text{meth-} \\ 2&\text{eth-} \\ 3&\text{prop-}\\4 & \text{but-}\\5 & \text{pent-} \\ 6 & \text{hex-} \\ 7 & \text{hept-} \\8 & \text{oct-}\\ \dots & \dots\end{array}`.

• Name of this hydrocarbon: heptane;
• Prefix: hept-;
• Number of carbon atoms in the longest chain: 7.

Hence the structure:

`\text{CH}_3\text{-CH}_2\text{-CH}_2\text{-CH}_2\text{-CH}_2\text{-CH}_2\text{-CH}_3`.

All the
`\text{-CH}_2\text{-}` in the formula might look redundant. "
`\text{CH}_2`" appears five times in a row and may be condensed into
`(\text{CH}_2)_5`. Hence the condensed formula:

`\text{CH}_3\text{-}{(\text{CH}_2)_(\bf5)\text{-CH}_3`.

Therefore
`n = 5`.