2-methylpropan-1-ol. (1) (b) Triethanol amine and triisopropyl amine are bases used to neutralise acidic compounds in the hairspray to prevent damage to the hair. In terms of the intermolecular bonding present, explain clearly why triethanol amine has a much higher boiling point than triisopropyl amine. (2) 23. Chocolate contains various compounds. (a) Many of the flavour and aroma molecules found in chocolate are aldehydes and ketones. Two examples are shown below. Phenylethanal can be easily oxidised but 1,3-diphenylpropan-2-one cannot. (i) Name a chemical that could be used to distinguish between these two compounds. (1) (ii) Name the type of organic compound formed when phenylethanal is oxidised. (1) (b) Glycerol monostearate is an emulsifier used in chocolate. (i) Why is glycerol monostearate added to chocolate? (1) (ii) Draw a structural formula for glycerol. (1) (c) Theobromine, a compound present in chocolate, can cause illness in dogs and cats. To decide if treatment is necessary, vets must calculate the mass of theobromine consumed. 1·0 g of chocolate contains 1·4 mg of theobromine. Calculate the mass, in mg, of theobromine in a 17 g biscuit of which 28% is chocolate. Show your working clearly. (2) (d) The flavour and texture of chocolate comes from a blend of compounds. your knowledge of chemistry, describe how you could show that there are ionic compounds and covalent compounds present in chocolate. (3) 24. Ethanol has many uses. (a) Ethanol is found at relatively low concentrations in wine.
2-methylpropan-1-ol. (1) (b) Triethanol amine and triisopropyl amine are bases used to neutralise acidic compounds in the hairspray to prevent damage to the hair. In terms of the intermolecular bonding present, explain clearly why triethanol amine has a much higher boiling point than triisopropyl amine. (2) 23. Chocolate contains various compounds. (a) Many of the flavour and aroma molecules found in chocolate are aldehydes and ketones. Two examples are shown below. Phenylethanal can be easily oxidised but 1,3-diphenylpropan-2-one cannot. (i) Name a chemical that could be used to distinguish between these two compounds. (1) (ii) Name the type of organic compound formed when phenylethanal is oxidised. (1) (b) Glycerol monostearate is an emulsifier used in chocolate. (i) Why is glycerol monostearate added to chocolate? (1) (ii) Draw a structural formula for glycerol. (1) (c) Theobromine, a compound present in chocolate, can cause illness in dogs and cats. To decide if treatment is necessary, vets must calculate the mass of theobromine consumed. 1·0 g of chocolate contains 1·4 mg of theobromine. Calculate the mass, in mg, of theobromine in a 17 g biscuit of which 28% is chocolate. Show your working clearly. (2) (d) The flavour and texture of chocolate comes from a blend of compounds. your knowledge of chemistry, describe how you could show that there are ionic compounds and covalent compounds present in chocolate. (3) 24. Ethanol has many uses. (a) Ethanol is found at relatively low concentrations in wine.
Chemistry-S5-Higher-Natures-Chemistry-Homework-past-papers.docx