Lesmahagow High School Higher Chemistry Alcohols and Esters - Past Paper Homework Questions
. Carbohydrates are an essential part of our diet. (a) Why are carbohydrates an important part of our diet? (b) Name the elements present in carbohydrates. (c) A student tested the carbohydrates glucose, sucrose and starch as shown. Copy and complete the table by identifying each carbohydrate. 2 (4) 2
2. The fermentation of glucose is catalysed by the enzyme zymase. (a) Balance the equation. (b) A series of fermentation experiments was carried out at different temperatures and the volume of carbon dioxide was measured.. (i) Plot a line graph of these results, showing the temperature of the reaction against the volume of CO 2 collected. (ii) When the experiment was carried out at 70 o C, no carbon dioxide was produced. Suggest a reason for this. (3) 3
3. (a) Draw the full structural formula for ethanol. (b) The dehydration of ethanol to ethane was carried out using the following apparatus. (i) Complete the word equation for the reaction Ethanol Ethene + (i) As a safety precaution, the delivery tube was removed from the water before heating was stopped. Why was this done? (ii) What would the mass of aluminium oxide catalyst be after the reaction was complete? (4) 4
4. Infrared spectroscopy can be used to detect the bonds present in molecules. The same bond always absorbs infrared radiation at the same wavenumber, even in different molecules. For example the C H bond absorbs in the range 2800 3000 wavenumbers. The infrared spectra of two different organic compounds are shown. (a) The absorption at wavenumber 600 in the spectrum of butane is not present in the spectrum of propane. Which bond could be responsible for this absorption/ (b) The O-H bond absorbs in the ranger 3500-3700 wavenumbers. Sketch the infrared spectrum you would predict for ethanol. (2) 5
5. (a) Draw the full structural formula for propanoic acid. (b) The diagram below shows how an alkane can be prepared from an alkanoic acid. The equation for the reaction is: alkanoic acid alkane + carbon dioxide Copy and complete the table to show which alkanoic acid could be used to produce butane. Alkanoic acid ethanoic acid propanoic acid Alkane methane ethane 6
butane (2) 6. The flow chart shows some of the stages in the manufacture of ethanoic acid. (a) In the mashing process, some of the starch is broken down into glucose. Using the flow chart, write the word equation for the reaction taking place in the mashing process. (b) Name process X. (c) Draw the full structural formula for ethanoic acid (d) Ethanoic acid can be reacted with methanol to form an ester, which is used as a solvent in nail varnish remover. Name this ester (4) 7
7. Hydroxy acids are compounds that contain both a hydroxyl group and a carboxylic acid group within the same molecule. These compounds are able to form cyclic esters called lactones. (a) Draw the structural formula for the lactone formed when this hydroxyl acid reacts. (b) Draw the structural formula for the hydroxyl acid from which this lactone was formed. (2) 8
8. Ethyl ethanoate can be made by reacting ethanoic acid and ethanol. (a) Name this type of chemical reaction. (b) A method of making ethyl ethanoate from ethanol only, has been developed. 2C 2 H 5 OH CH 3 COOC 2 H 5 + 2X (i) Name substance X. (ii) This method was developed for use in countries where ethanol is made from a renewable source. Name this source of ethanol. (3) 9
9. The diagram shows how an ester with a pear drops smell can be made. (c) (i) Name the ester formed. (ii) Why can this reaction be described as a condensation reaction? (2) 0
0. Lavender flowers contain an oil. (a) Lavender oil is produced from the flowers by steam distillation. The flowers are put into a flask with a little water. Steam from a steam generator is blown through them to extract the oil. The mixture of lavender oil and steam distils over. It is condensed and collected. The pieces of apparatus which are used to carry out this steam distillation are shown below. Put a letter in each box to show the order in which the pieces of apparatus should be arranged to obtain the mixture.
(continued) (b) The structural formulae for two of the compounds in lavender are shown below. (i) To show that lavender oil contains unsaturated compounds it can be tested by shaking a sample with bromine solution. Bromine solution is corrosive. Apart from wearing safety goggles, give another safety precaution which should be taken when shaking the sample with bromine solution. (ii) Linalool is an alcohol. CAREFULLY copy the structure of linalool and circle the alcohol group in the linalool molecule.. (iii) Linalyl ethanoate is made from an alcohol and ethanoic acid. To which group of compounds does linalyl ethanoate belong? (4) 2