Alcohols & Carboxylic Acids Practice Questions

Which of these is the formula of butan-1-ol?

A $\mathrm{C_4H_8}$

B $\mathrm{C_4H_9OH}$

C $\mathrm{C_4H_{10}}$

D $\mathrm{C_3H_7OH}$

Draw the structure of a molecule of ethanol, showing all covalent bonds.

A student writes the formula of an alcohol as $\mathrm{C_3H_7OH}$.

Give the name of this alcohol.

Give the formula of propanoic acid.

Draw the structure of a molecule of ethanoic acid, showing all covalent bonds.

Name the substance that is added to the sugar solution to provide the enzymes needed for fermentation.

Complete the word equation for the fermentation of glucose.

glucose $\rightarrow$ .......................... + ..........................

Give two conditions, other than the presence of yeast, that are needed for the sugar to ferment successfully.

Give two variables the student must keep the same each time, so that the alcohols can be compared fairly.

The student weighs the spirit burner, with its cap on, before and after burning each alcohol.

Explain why these two masses are needed.

The energy released per gram calculated by the student is much lower than the value given in a data book.

Suggest two changes to the apparatus or method that would give a result closer to the data book value.

Calculate the temperature rise of the water when propan-1-ol was burned.

Calculate the energy, in joules, transferred to the water when the ethanol was burned.

Use the equation

$Q = m \times c \times \Delta T$

where the mass of water $m = 100\ \mathrm{g}$ and the specific heat capacity of water $c = 4.2\ \mathrm{J/g/^\circ C}$.

Use your answer to (b) to calculate the energy released per gram of ethanol burned.

The student concludes that pentan-1-ol releases the most energy per gram of the four alcohols.

Use the data in the table to explain how the results support this conclusion.

Write the word equation for the oxidation of ethanol when it is exposed to air.

Butan-1-ol can be oxidised in a similar way.

Name the carboxylic acid produced when butan-1-ol is oxidised.

Write a balanced equation for the oxidation of butan-1-ol, $\mathrm{C_4H_9OH}$, to the carboxylic acid in (b).

State what is removed from an alcohol molecule when the alcohol is dehydrated.

Butan-1-ol, $\mathrm{C_4H_9OH}$, is dehydrated to form butene.

Write the balanced equation for this reaction.

Ethanol can be dehydrated in the same way.

Draw the structure of the molecule formed, showing all covalent bonds.

A fermentation mixture made from sugar solution and yeast contains about 12% ethanol by volume. The rest of the liquid is mostly water.

• boiling point of ethanol = 78 °C
• boiling point of water = 100 °C

The mixture is filtered and then fractionally distilled in the laboratory using a flask, a fractionating column, a thermometer and a condenser.

Explain how fractional distillation of this mixture produces a much more concentrated solution of ethanol.

A spatula of solid sodium carbonate is added to a test tube of vinegar.

Describe what would be seen, and name the gas produced.

Write the balanced equation for the reaction between ethanoic acid, $\mathrm{CH_3COOH}$, and sodium carbonate, $\mathrm{Na_2CO_3}$.

Propanoic acid is in the same homologous series as ethanoic acid.

A piece of magnesium ribbon is added to a solution of propanoic acid.

Name the salt formed and give the formula of the other product.