higher chemistry - unit 2

Alternative transcript:

forms an "'-anoate' salt examples C-O- contain an eater link functional group ● • formed by reacting alcohol with carboxylic acid name comes from alcohol and acid (eg. Pent-1-01 with ethano (acid = pentyl ethanoat + + making esters J uses of esters smell and taste: flavourings and perfumes non-polar industrial solvents (compounds clon`'t dissolve in H₂O making an ester = condensation. breaking an ester = hydrolysis methyl ethanoate & water →> methanol + ethanoic acid (H) ethanol hexanoic acid →→ethyl hexanoate & water (c) an ester Use H₂SO4 as - use water bath as mixture very flammable add resulting mixture to Sodium hydro carbonate to a catalyst nutralise H₂SO4 wet paper towel used to condense the ester in gas State back to liquid wet paper towel hot water carboxylic acid alcohol + H₂SO4 ester making oily Tayer water and sodium hydrogen carbonate ● ● fats and Oils they're a concentrated source of energy essential for the transport and storage of fat-Soluble vitamins in the body. Properties of fats and oils. non-polar molecules (allow vitamins to dissolve in them that wouldn't dissolve in water) + fats are solid at room temp, oils are liquids + fats have a higher mpt than oils. edible fats and oils structures - naturally occuring esters made from the same alcohol (glycerol) OH H-Ć-Ć-Ć-H Systematic name for glycerol is propan - 1,2,3-triol t 4 the carboxylic acid used to fake fats are called Fatty Acids - they can be called triglycerides as they have 3 fatty acids joined to one glycerol (3:1) fats are saturated > 1 - oils are unsaturated 011 HO - OH U=O FO with 3 ester links, with long carbon chains. fats + pack closely forming together. tightly means stronger van der can form Waals 5= Solid S Saturated 5= single HO. HO- 11 + 0 11 O Oils molecules can't pack. so closely + weak (DF's + oils can be hardened by reacting with hydrogen over a nickel catalyst + makes oils more saturated Soaps and detergents Soaps are made when a fatty acid is neutralised Soaps are a water-soluble salt of a fatty acid alkaline hydrolysis (making soaps) + alkaline used as a catalyst in a hydrolysis reaction + reactants are edibie fats/oils and an alkali + products are soap molecules and glycerol Structure 1 poiar, water soluble hydrophilic MX non poiar, oil soluble, hydrophobic ↑ ●Carbon oxygen. • hydrogen sodium carboxylate head Na = double bund ...ionic band how scaps clean 1. Soap molecules dissolve in water: the Nation separates leaving the non-polar tail 2 che non-polar tail is attracted to and dissolves in the non-polar dirt 3. when the water is agitated the soap molecules start to lift off the dirt 4 continuing until scap molecules separate the dirt into small droplets Surrounded by Soap molecules (miscellars) 5. Finally, soap molecules surround all the dirt into structures, that repel eachother because the negative charges remain suspended in water. to be rinsed away. hard water - water that contains high levels of dissolved metal ions (Ca + mg) Problems - Scaps form scum with hard water (an insoluble precipitate) Soapless detergents + + to avoid soap forming scum, soapless detergents used instead have non polar hydrophobic tails. + ionic hydrophilic heads. + contain a Sulfariate ion instead of a carboxylate ion like soap • contain small droplets of one liquid dispersed in another immiscible liquid • a chemical that can be used to prevent non-polar and polar liquids separating into layers. types of emulsions + oil-in-water emulsion (oil dropiets suspended in water) + water-in-oil emulsion (water droplets suspended in oil). emulsifiers made by reacting edible oils with glycerol to form molecules in which one or two fatty acid groups are linked to a glycerol backbone rather than 3 found in edible oils. + the one or two hydroxyl groups present in these molecules are hydrophilic whilst the fatly chains are hydrophobic the hydrophobic fatty acid chain dissolves in oil whilst the hydrophilic hydroxyl group dissolves in water, forming stable emvision + + HO- emulsions HO CH₂ Polar i CH ₂ H2 с 0= CH₂ 1 CH₂ CH₂ CH₂ CH₂ non-Polar 1 CH₂ CH₂ CH3 a common food emulsifiers • made by reacting edible oils with giacerol, but leaving one or two hydroxyl group tree on the glycerol backbone eg. Salad dressings, mayonnaise, milk, whipped/ice cream C also found in non-edible substances Leg. moisturisers, paint 15 ● the major structural materials of animal tissues involved in maintainance and regulation of life processes up of different combos of amino acids madle amino acids 141 N Proteins R J amino group | C-n H OH formation of proteins 요 carboxyl group R. group 4 - essential amino acids are needed to be consumed as body can't make them - Small molecule made when amino acids join H₂O the reaction that takes place is conclensation Peptide bond. hydrolysis of proteins water must be added to split the protein molecule shapes of proteins long chain protein molecules form spirals, sheets + complex Shapes inter-molecular forces between chains hold shape (H bonds) enzymes biological catalysts made of protein. centuring proteins is when proteins change shape as the intermolecular forces break. heat during cooking causes denturing changes the texture of food e.g eggs Aldehydes • contain a carbonyl functional group functional group at end of molecule general formula CnH₂nO O Oxidation of Alcohols and foods. 0 add flavour and aroma to molecules. have an -anal ending (methanal) Ketones • contain a carbonyl functional group functional group in middle of molecule. general formula CnH₂nO • have an -anone ending (hexan-2-one) Oxidation of alcohols Primary Alcohol • Aldehyde Secondary Alcohol + Ketone X oxidising agents to differentiate Fehling Solution Blue Brick red Tollens reagent - Colourless → Silver Mirror Acidified dichromate = Orange → Green Hot copper (11) oxide Black Tertiary Alcohol = = 요 -C-H 0=0 - Brown Solid H ¡ H-C- C- J I 4 H X 0=0 -C-H H H O H-C-C-C-H 1 H Carboxylic Acid H i 1 H - for Aldehyde's 17 18 ● O Antioxidants antioxidants prevent unwanted oxidation reactions. Substances easily oxidised so they can protect and be oxidised in place of the compounds added to can be recognised from a redox equation example vitamin c Сонд Ов C₁H ₂0₁ + 2H² + 2e- + oxygen from the air cause the oxication of food. + the oxidation of edible oils gives food a rancid flavour essential oils concentrated extracts of volatile (evaporate easy), non-water Soluble (hydrophobic) aroma compounds from plants Terpenes unsaturated compounds formed by joining together isoprene units. isoprenes CH3 1 Fragrances H₂C с C= H CH₂ - known as 2-methylbuta-1,3-diene -molecular formula G5 H8 - find how many isoprene units: clivide total number of carbons by 5 1st step 2nd step 3rd step ● 0 - + = Skincare and free radicals ultra-violet (uv) light high energy form of light, present in sunlight. can supply molecules with enough energy to split molecules and atoms causes sunburn and skin ageing accelerates free radical atoms/molecules highly reactive due to presence of unpaired electr • formed when UV light breaks bonds. Chain reactions Initiation = Sunblock-prevents uv light from reaching the skin by providing a physical barrier or chemical that absorbs radiation. - free radicals form by breaking bonds CL-CL→ 2 CL e.g Propagation - using up a free radical and making another eg C₁²° + H-H → H-Cl + H² H° C-CL → H-CL + C₁° = Termination - free radicals react with other free radicals e.g cit cl² → Cl₂ H² + H² H₂ free radical scavenger molecules that react with free radicals to form stable molecules and prevent chain reactions from occurring added to cosmetic products (skin creams) - food products to prevent oxidation. - plastics to stop plastic becoming bitter