1. Complete the table NameFormulaStructure+ O 2 Miscibility in water methaneCH 4 CO 2 + H 2 OImmiscible ethaneC2H6C2H6 CO 2 + H 2 OImmiscible propaneC3H8C3H8 CO 2 + H 2 OImmiscible butaneC 4 H 10 CO 2 + H 2 OImmiscible

2. Alcohols What does the word alcohol mean to you? Like the alkanes the alcohols are a series of related compounds They all contain an –OH group – a functional group The –OH group allows them to ‘hydrogen bond’ like water does – so boiling points are higher than for the equivalent alkane

3. Structures ethanol C 2 H 5 OH propanol C 3 H 7 OH butanol C 4 H 9 OH

4. Reactions + oxygen: burn to give CO 2 and H 2 O C 2 H 5 OH (l) + 3 O 2 (g)  2 CO 2 (g) + 3 H 2 O (l) + water: miscible + sodium: reacts slowly producing hydrogen gas and sodium ethoxide 2 C 2 H 5 OH + 2 Na  2 C 2 H 5 O - Na + + H 2 c.f. 2 Na + 2 H 2 O  2 NaOH + H 2

5. Learning objective: To illustrate the practical importance of carboxylic acids To demonstrate that carboxylic acids in solution show the characteristic reactions of acids To introduce the –COOH functional group in carboxylic acids To practise writing balanced equations to describe the reactions of carboxylic acids To introduce esters as products of the reactions of alcohols with carboxylic acids To observe properties of esters 13/06/2016

6. Carboxylic acids Include the –COOH functional group -C=O O H Dissolves in water to form: e.g. CH 3 COOH CH 3 COO - + H + Carboxylic acids react in the same way as acids – but because they are only partially ionised at any one time they react more slowly – the concentration of [H + ] is less than with, for example, HCl. They are weak acids

8. Practical

9. TestObservationsNotes Smell e.g. vinegarShows that there are volatile molecules i.e. does not separate fully into ions as HCl (aq) does. pH of a solution of the carboxylic acid solution  3-4 Weakly acidic Reaction with magnesium metal Slow fizzing Produces hydrogen gas & salt 2 HCOOH (aq) + Mg (s)  (HCOO) 2 Mg (aq) + H 2 (g) Reaction with copper oxide Produces coloured salt 2 CH 3 COOH (aq) + CuO (s)  (CH 3 COO) 2 Cu (aq) + H 2 O (l) Reaction with sodium carbonate Fizzes Produces carbon dioxide 2 HCOOH (aq) + Na 2 CO 3 (s)  2HCOONa (aq) + H 2 O (l) + CO 2 (g)

10. Salts of carboxylic acids Called carboxylates Contain RCOO - group Sodium ethanoate dissolves to give CH 3 COONa (s)  CH 3 COO - (aq) + Na + (aq) sodium ethanoate  ethanoate ions + sodium ions REMINDER Parents’ Evening – Thursday 10 th February Coursework due – Monday 14 th February

11. Learning objective: To introduce esters as products of the reactions of alcohols with carboxylic acids To observe properties of esters To demonstrate the procedure for making an ester on a laboratory scale To explain the purposes of practical techniques involved in the preparation of an ester 13/06/2016 Complete first section of carboxylic acids and esters sheet

12. Making Esters Why is it necessary to heat the test tubes? Why should you heat them in a water bath, not directly in a flame? What is the purpose of adding concentrated sulfuric acid to the mixture of the organic acid and the alcohol? Suggest why you poured the mixture into sodium carbonate solution, not just water. Use the example of esters and water to explain what the work ‘immiscible’ means.

13. 1.Add 10 g ethanoic acid and 8 g ethanol to the distillation flask. Swirl and carefully add 2 cm 3 concentrated sulfuric acid. 2.Fit a reflux condenser and heat gently for 10 minutes. Cool. 3.Rearrange the apparatus for distillation. Distil off everything up to 82 °C. (Clean the distillation apparatus for step 6.) 4.Transfer the distillate to a tap funnel. Taking the usual precautions to release gases, shake first with sodium carbonate solution to remove acids and then with calcium chloride solution to remove unchanged ethanol. In both instances run off and discard the lower, aqueous layer. 5.Transfer to a small flask. Add a few granules of anhydrous calcium chloride. Stand for a few minutes until the liquid is clear. 6.Redistil from the clean distillation apparatus and collect the fraction boiling in the range 74–79 °C.

14. Structure and naming acid + alcohol  ester + water ethanoic acid + methanol  methyl ethanoate + water propanoic acid + butanol  butyl propanoate + water

15. Ester Functional group I C=O I O I H-C-H I The oxygens are not directly bonded to the hydrogens The molecule does not form hydrogen bonds so do not mix well with water Esters are much more volatile (evaporate more easily) than the alcohol and acid that form them

16. ethanol propanoic acid ethyl propanoate water

18. 1.Add 10 g ethanoic acid and 8 g ethanol to the distillation flask. Swirl and carefully add 2 cm 3 concentrated sulfuric acid. 2.Fit a reflux condenser and heat gently for 10 minutes. Cool. 3.Rearrange the apparatus for distillation. Distil off everything up to 82 °C. (Clean the distillation apparatus for step 6.) 4.Transfer the distillate to a tap funnel. Taking the usual precautions to release gases, shake first with sodium carbonate solution to remove acids and then with calcium chloride solution to remove unchanged ethanol. In both instances run off and discard the lower, aqueous layer. 5.Transfer to a small flask. Add a few granules of anhydrous calcium chloride. Stand for a few minutes until the liquid is clear. 6.Redistil from the clean distillation apparatus and collect the fraction boiling in the range 74–79 °C. Heat under reflux - preparation Fractional distillation - purification Separating aqueous layer - purification Drying with anhydrous CaCl 2 - purification Fractional distillation - purification

19. Fats and oils

20. Naturally occuring Animal fat Vegetable oilMarine oil lard suet sunflower oil coconut oil cod liver oil whale oil

21. Homework Find out about the issues around trans fats. You need to make bullet points on: –The sources, structure and properties of saturated and unsaturated fats –The difference between cis and trans fats in terms of molecular structure –A description and explanation of the effect that cis and trans structures have on properties –Explain how oils are hardened –Explain the problems with the trans fats formed when oils are hardened

22. Fats and oils glycerol Systematic name is propane-1,2,3-triol Fats and oils are built from an alcohol with three -O-H groups.

23. Fats and oils Stearic acid Systematic name is octadecanoic acid The other components of fat molecules are carboxylic acids such as

24. Fats and oils Fats and oils are ESTERS of glycerol and long chain carboxylic acids

25. Fats and oils Removal of water in the condensation reaction gives - The molecular formula shown above suggests that the fat molecule is shaped like an E, but the molecule is actually shaped more like this:

26. Fats and oils Fats are mainly built from carboxylic acids with C-C single bonds. Oils have some C=C bonds in the carboxylic acids from which they are made. Stearic acid in beef fat Oleic acid in olive oil Carbon – carbon (>C=C<) double bond here

27. Oil Fat Fat molecules pack together more tightly, making fats solid at room temperature. This is like he difference between ldpe and hdpe last year Double bonds in oil make the molecule less compact. Less tightly packed molecules make oils liquid. Fats and oils

28. Testing for unsaturation Carbon-carbon double bonds (>C=C<) decolourise bromine water

29. Fats and oils that fats and oils are esters of glycerol with fatty acids. that unsaturated compounds can be recognised by the presence of C= C double bonds.