(a) What term is used to describe each of the following processes? (i) Alkaline hydrolysis of fats and oils; (ii) The conversion of glucose into ethanol by ...
Question 1 Report
(a) What term is used to describe each of the following processes?
(i) Alkaline hydrolysis of fats and oils;
(ii) The conversion of glucose into ethanol by enzymatic action;
(iii) Thermal decomposition of higher petroleum fractions into lower molecular mass hydrocarbons in the presence of catalyst.
(b)(i) Write the structure and IUPAC name for one alkanoic acid with the molecular formula C\(_4\)H\(_8\)0\(_2\).
(ii) Arrange the following compounds in order of increasing boiling point: Butane; Butanoic acid; Methylpropane.
(iii) Give an explanation for your answer in (b)(ii).
(c)(i) Ethanol was used for preparing a gas X which decolorized bromine water. Identify X and describe briefly its laboratory preparation.
(ii) Write an equation to show how ethanol reacts with sodium
(iii) Give the reagent and reaction conditions for the conversion of ethanol into C\(_2\)H\(_5\)COOC\(_2\)H\(_5\).
(d) State the type of recction involved in each of the conversions indicated below:
(i)C\(_6\)H\(_6\)C\(_6\)H\(_5\)CH\(_3\)
(ii) nC\(_2\)H\(_4\) \(\to\) (CH\(_2\) - CH\(_2\)),
(iii) CH\(_3\)CH\(_2\)CH(OH)CH\(_3\) -> CH\(_3\)CH\(_2\)CCH\(_3\)
(iv) (C\(_6\)H\(_{10}\)O\(_5\)) -> C\(_6\)H\(_{12}\)O\(_6\).
(iv) 
Answer Details
(a) Terms for the processes
- Alkaline hydrolysis of fats and oils: saponification.
- Conversion of glucose into ethanol by enzymes: fermentation.
- Thermal decomposition of higher petroleum fractions into lower ones over a catalyst: (catalytic) cracking.
(b)(i) Alkanoic acid with molecular formula C4H8O2: butanoic acid, CH3CH2CH2COOH.
(ii) Increasing boiling point: methylpropane < butane < butanoic acid.
(iii) Explanation: methylpropane and butane are isomers (C4H10). The branched methylpropane has a smaller surface area, so its van der Waals forces are weakest and its boiling point is lowest. Straight-chain butane has a larger contact area and stronger van der Waals forces, so a higher boiling point. Butanoic acid molecules are joined by strong hydrogen bonds through the -COOH group, giving the highest boiling point.
(c)(i) X is ethene (ethylene), C2H4, which decolorizes bromine water. Preparation: heat ethanol with excess concentrated tetraoxosulphate(VI) acid at about 170°C, which dehydrates the ethanol; alternatively pass ethanol vapour over heated aluminium oxide or broken porcelain. The gas is collected over water. \[\text{C}_2\text{H}_5\text{OH} \xrightarrow[170^\circ\text{C}]{\text{conc. H}_2\text{SO}_4} \text{C}_2\text{H}_4 + \text{H}_2\text{O}\]
(ii) Ethanol with sodium: \[2\text{C}_2\text{H}_5\text{OH} + 2\text{Na} \rightarrow 2\text{C}_2\text{H}_5\text{ONa} + \text{H}_2\]
(iii) Conversion of ethanol into C2H5COOC2H5 (ethyl propanoate): warm the ethanol with propanoic acid (C2H5COOH) using a few drops of concentrated H2SO4 as catalyst (esterification). \[\text{C}_2\text{H}_5\text{COOH} + \text{C}_2\text{H}_5\text{OH} \underset{\text{conc. H}_2\text{SO}_4}{\rightleftharpoons} \text{C}_2\text{H}_5\text{COOC}_2\text{H}_5 + \text{H}_2\text{O}\]
(d) Type of reaction in each conversion
- C6H6 to C6H5CH3: substitution.
- nC2H4 to (CH2-CH2)n: addition polymerization.
- CH3CH2CH(OH)CH3 to CH3CH2COCH3: oxidation.
- (C6H10O5)n to C6H12O6: hydrolysis.
The reaction shown in the diagram is a cyclic diene combining with ethene across the double bonds to form a fused ring product, with no small molecule eliminated. This is an addition reaction (a cycloaddition).
Download The App On Google Playstore
Everything you need to excel in your exams
