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Carbohydrates

Carbohydrates are compounds made of Carbon, Hydrogen and Oxygen. They are made in PHOTOSYNTHESIS This process is carried out in the leaves of Green Plants.

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Carbohydrates

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  1. Carbohydrates are compounds made of Carbon, Hydrogen and Oxygen. They are made in PHOTOSYNTHESIS This process is carried out in the leaves of Green Plants. Green plants contain a special pigment called CHLOROPHYLL which traps sunlight. Plants use this energy along with CO2 gas and Water to make food – Glucose (sugar), Oxygen is also released. CO2 + H2O —>O2 + C6H12O6 Light and Chlorophyll must be present for the reaction to take place. Carbohydrates

  2. Examples of Carbohydrates • Carbohydrates contain the elements C.H. and O. • There are twice as many H in the molecules as C and O. • They can be split into 3 main groups: monosaccharides, disaccharides and polysaccharides.( saccharide = sugar group) • Monosacharides – formula C6H12O6 e.g. glucose, fructose and galactose. They are isomers. • Disaccharides – formula C12H22O11 e.g.. Lactose, maltose, sucrose. They are isomers • Polysaccharides – (C6H10O5)n e.g.. Cellulose, starch, glycogen.

  3. Respiration is when Carbohydrates are broken down to release energy. Oxygen must be present. CO2 and H2O are produced. C6H12O6 +O2 —>CO2 + H2O ( energy is released) When we eat food the energy trapped in the food is released. We can show that energy is contained in food in the lab. Example Exploding custard tin. When we burn sugar in the lab we can test the products. We use lime water and collect the colourless liquid produced in a U tube. (CO2 + H2O) Respiration

  4. These 2 reactions working together make part of the Carbon Cycle. Humans can destroy the balance by: Burning – CO2 is produced. Chopping down trees/plants- less photosynthesis therefore too much CO2 and less O2 in the atmosphere. When any C compound is burned CO2 is produced ( Fossil Fuels) Photosynthesis and respiration are the chemical opposites of one another. When they work together without intervention they ensure the correct balance of gases in the air. We breathe out CO2. Plants use this in Photosynthesis. They give out O2. We require this for respiration. Plants go through respiration when there is no sunlight. The Carbon Cycle

  5. Iodine test Starch will turn Iodine solution from brown to blue/black. Benedict’s Test (Fehling’s) Monosaccharides and disaccharides – except sucrose will turn Benedict's reagent from blue to orange. Testing for Carbohydrates

  6. Mono and disaccharides are usually soluble in water. If you shine a beam of light through it, the light will pass strait through. They are sweet tasting. Starch is not sweet tasting. It forms a colloid in water – it looks as if it has dissolved but if you shine a beam of light through it you can see the particles. The molecules are too big to dissolve. Properties of Carbohydrates

  7. Making long chain Carbohydrates • Disaccharides and polysaccharides are made when monosaccharides undergo condensation polymerisation. 1 water molecule is released for every two monomers joined. • Example • Glucose +Glucose —> maltose + water • C6H12O6 + C6H12O6 —> C12H22O11 + H2O

  8. Breaking Long Chain Carbohydrates • Hydrolysis is the break down of Carbohydrates into smaller molecules. E.g. Starch being broken down into Glucose. This is the opposite ofpolymerisation. A water molecule has to be added back – hydrolysis. • An acid or enzyme has to be present for this to happen. • Sucrose breaks down to give 1 fructose molecule and 1 glucose molecule. • Sucrose —> glucose + fructose C12H22O11 Acid/enzyme C6H12O6 +C6H12O6

  9. Digestion • When we eat starchy food our bodies break it down into smaller molecules so they can pass through the gut wall into the blood. • This is another example of Hydrolysis. • It starts off in the mouth. Saliva contains an enzyme, amylase, which starts to break down the starch.It continues in the stomach, where acid is found. • (C6H10O5)n—>C6H12O6 • Acid/enzyme

  10. Digestion in the lab • Place starch solution in 3 different test-tubes • To one add amylase • To another add acid • Add nothing to the third • Place all 3 in water bath at 37C ( body T) • Test each test-tube with Benedict’s solution after a few minutes. • The test-tubes with the acid and amylase will turn orange – proving the starch has been broken down into glucose.

  11. Look at how far each spot has travelled. Compare the spots of the mono and disaccharides with H1 and H2. Match up the spots at same level to identify the which type of sugar is produced in Hydrolysis. We can use CHROMATOGRAPHY Spot the paper with:the products of hydrolysis of starch(H1) and sucrose(H2) and mono and disaccharides. Do not mix the spots. Let the chromatography run. Look at results Identifying the products of Digestion/Hydrolysis

  12. Equation C6H12O6 →C2H5OH +CO2 C2H5OH is ethanol. It is part of the Alkanols. This is another homologous series. This is the process of making Alcohol from sugar. Small sugar molecules can be converted to alcohol, using the enzyme Zymase, which is found in yeast. Carbon dioxide is also released. Fermentation

  13. Alcohol slows down our reactions. Too much can damage our livers. It can also be used as a fuel. You can make alcohol from any carbohydrate source. Source Alcohol Barley Beer/Whiskey Apples Cider Grapes Wine/Sherry Potatoes Vodka Alcoholic Drinks

  14. We place the impure alcohol in the distillation flask with antibumping granules. Heat up the mixture. Ethanol has BP of is 78C, water is 100C. The alcohol will boil first, pass along delivery tube and condense back to liquid. WE can repeat this process to purify it even more. Spirits are distilled. WE can increase the strength of alcohol by distilling it. This removes any impurities.( normal alcohol concentration in fermentation is 15% - any stronger and the enzyme is destroyed – DENATURED) Distillation

  15. Step 3 Fermentation Yeast added – Glucose brakes down into ethanol and Carbon dioxide Step 4 – Distilling To purify whisky – increase concentration. Step 5 – Blending Mix different whisky’s then bottle them( malt whisky - not blended) Step 1 – Malting Barley is Hydrolysed into Maltose (uses enzyme in Barley) – Green Malt Step 2 – Mashing Green Malt roasted on peat fire and Mashed Making Whisky

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