Question

A compound containing only carbon and hydrogen is 85.63% C by mass. Reaction of this compound with H₂O produces a secondary alcohol as the major product and a primary alcohol as the minor product (see Exercise 58). If the molar mass of the hydrocarbon is between 50 g/mol and 60 g/mol, name the compound.

Short answer

The name of the compound is 1-butene

Step-by-step solution

Given data

To be able to name the compound described in the problem, we must make use of the given values. We were given the following values:

Percentage of Carbon= 85.63%

Percentage of Hydrogen= 100-85.63=14.37%

50g/mol<Mass of Hydrocarbon<60g/mol

First, using the given values, we must calculate for the empirical formula of the compound using the individual atoms present in the compound:

$$\begin{gathered} \mathrm{Carbon}\frac{85.63}{12}=7.13;\frac{7.13}{7.13}=1;1\mathrm{Carbon}\mathrm{atom} \\ \mathrm{Hydrogen}\frac{14.37}{1}=14.37;\frac{14.37}{7.13}=2;2\mathrm{Hydrogen}\mathrm{atoms} \end{gathered}$$

Thus, the empirical formula of the compoundis CH₂

The empirical formula

Now that we know the empirical formula, to be able to find the mass, first we must use the given_{$\text{60 g/mol}$} to be able to know the specific amount of the ratio given by the empirical formula.

Hence,

_{$\mathrm{n}=\frac{60}{14}=4.28;\mathrm{Approximately}\mathrm{four}\mathrm{times}$}

Finally, we can say that the molecular mass of the compound with four times the empirical formula fits the description of compound in the problem

_{$\mathrm{Molar}\mathrm{Mass}=2\left(\mathrm{Mass}\mathrm{of}{\mathrm{CH}}_2\right)=2\left(14.027\right)=56.106\mathrm{g}/\mathrm{mol}$}

  The compound with a molar mass

Considering that it fits the description of the compound with a molar mass greater than 50 and less than$60(50\mathrm{g}/\mathrm{mol}<\mathrm{molarmass}<60\mathrm{g}/\mathrm{mol})$the final compound is _{${\text{C}}_{\text{4}}{\text{H}}_{\text{8}}$}

To find the compound

There are various isomers of _{${\text{C}}_{\text{4}}{\text{H}}_{\text{8}}$}However, only alkenes will react with water to produce alcohol.

Since the compound has 4 carbons, it is a butane, and considering that it has only8 hydrogen atoms, one of its bonds is a C=C double bond, making it an alkene. The name of the structure is 1-butene or butane which will react with water to produce a secondary alcohol. 2-butene is not considered since it will not produce a minor product

Hence the name of the structure is 1-butene