Which conditions are required to obtain a good yield of a carboxylic acid when ethanol is oxidized using potassium dichromate(VI), ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7\left(\mathrm{aq}\right)$?

I. Add sulfuric acid

II. Heat the reaction mixture under reflux

III. Distil the product as the oxidizing agent is added

Alkenes are important starting materials for a variety of products.

State and explain the trend of the boiling points of the first five members of the alkene homologous series.

Describe two features of a homologous series.

The reaction of alkenes with bromine water provides a test for unsaturation in the laboratory. Describe the colour change when bromine water is added to chloroethene.

Deduce the Lewis structure of chloroethene and identify the formula of the repeating unit of the polymer poly(chloroethene).

Alkenes are an economically and chemically important family of organic compounds.

Besides polymerization, state two commercial uses of the reactions of alkenes.

State and explain whether the following molecules are primary, secondary, or tertiary halogenoalkanes.

Consider the following sequence of reactions:

${\mathrm{RCH}}_3\stackrel{\mathrm{reaction} 1}{\to }{\mathrm{RCH}}_2\mathrm{Br}\stackrel{\mathrm{reaction} 2}{\to }{\mathrm{RCH}}_2\mathrm{OH}\stackrel{\mathrm{reaction} 3}{\to }\mathrm{RCOOH}$

${\mathrm{RCH}}_3$ is an unknown alkane in which $\mathrm{R}$ represents an alkyl group.

The alkane contains $81.7\%$ by mass of carbon. Determine its empirical formula, showing your working

Consider the following sequence of reactions:

${\mathrm{RCH}}_3\stackrel{\mathrm{reaction} 1}{\to }{\mathrm{RCH}}_2\mathrm{Br}\stackrel{\mathrm{reaction} 2}{\to }{\mathrm{RCH}}_2\mathrm{OH}\stackrel{\mathrm{reaction} 3}{\to }\mathrm{RCOOH}$

${\mathrm{RCH}}_3$ is an unknown alkane in which $\mathrm{R}$ represents an alkyl group.

Equal volumes of carbon dioxide and the unknown alkane are found to have the same mass, measured to an accuracy of two significant figures, at the same temperature and pressure. Deduce the molecular formula of the alkane.