C7.4

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  • C7.4
    • Ethanol
      • The making of Ethanol
        • 1. Fermentation uses yeast to convert sugars into ethanol. Carbon dioxide is also produced
        • Sugar --> ethanol + carbon dioxide
        • 2. The yeast cell contains zymase, an enzyme that acts as a catalyst in fermentation
        • 3. Fermentation happens fastest at 30 degrees. This is because zymase works best at this temperature. At lower temperatures the reaction slows down
        • 4. Zymase also works best at PH 4- a strongly acidic or alkaline solution will stop it from working
        • 5. It is important to prevent oxygen getting to the fermentation process. Oxygen converts the ethanol to ethanoic acid, which lowers the PH
        • 6. When the concentration of ethanol reaches 10 to 20% the fermentation stops because the yeast gets killed off
      • Can it be concentrated by distilled
        • 1. The ethanol solution is put in a flask below a fractionating column
        • 2. The solution is heated so that the ethanol boils. The ethanol vapour travels up the column, cooling as it goes
        • 3. The temperature is such that anything with a higher boiling point than ethanol cools to a liquid and flows back into the solution at the bottom
        • 4. This means that only pure ethanol vapour reaches the top of the column
        • 5. The ethanol vapour flows through a condencer
      • Is fermentation sustainable
        • Will the raw materials run out
          • Sugar beet and yeast grow back quickly so will not run out
        • How good is the atom economy
          • The waste CO2 means it has a low atom economy
        • What do i do with my waste products
          • It can be released
        • What are the energy costs
          • Energy is needed to keep the reaction at its optimum
    • Making Ethanol
      • Biomass
        • Ethanol is made from biomass
        • 1. Waste biomass is the parts of a plant that would normally be thrown away
        • 2. Waste biomass can not be fermented in the normal way because it contains a lot of cellulose
        • 3. Eco li can be genetically modified to convert cellulose in waste biomass into ethanol
        • 4. The optimum conditions is a slightly acidic solution and a temperature of 35 degrees
      • Is it sustainable
        • The sustainability of the biomass method is very similar to the sustainability of the standerd fermentation method because they both use similar processes
      • Reactions
        • Fermentation is too slow for making ethanol on a large scale. Instead, ethanol is made on a industrial scale using ethane. This method allows high quality ethanol to be produced continuously and quickly
        • 1. Ethane is one of the hydrocarbons found in crude oil
        • 2. It is split to form ethane and hydrogen gas
        • Ethene will react with steam to make ethanol
        • The reaction needs a temperatre of 300 degrees and a pressure of 70. Phosperic acid is used as a catalyst
      • Sustainability
        • Crude oil and natural gas are non renewable and will run out
        • Crackin ethane has a fairly high atom economy as the  only waste product is hydrogen
        • The only waste is the hydrogen gas produced by cracking ethane
        • Energy is needed to maintain a high temperature and pressure used
        • This method has no specific impact on society
        • Manufacturing ethanol from ethane and steam is continuous
    • Esters
      • Functional group
        • COO
        • Esters are another family of organic chemicals
        • They are formed from an alcohol and a carboxylic acid
          • Esterification reaction
        • To start teh reaction you need to add a strong acid catalyst to mix
      • Uses
        • Many esters have pleasant smells
        • They are volatile
        • Esters are also used to make flavourings and aromas
        • Some esters are used as solvents
        • Plasticisers
      • How to make an ester
        • 1. Refluxing= The reaction
          • To make ethyl ethanoate you need to react ethanol with ethanoic acid using a catalyst such as concentrated sulfuric acid to speed things up
          • Heating the mixture also speds up the reaction- but you can not just stick a bunsen burner under it as it will catch fire
          • Instead, the mixture genly heated in a flask fitted with a condenser this catches teh vapours and recycles them back into the flask which gives them time to react
        • 2.Distilation
          • This separates your lovely ester from all the other stuff left in the flask
          • The mixture heated below a fractionating column and as it boils it goes up the fractionating column
        • 3. Purification
          • The liquid collected is poured into a tap funnel and tehated to remove its impurities as follows
            • The mixture is shaken with sodium carbonate solution to remove acidic solutions so teh mixture is seperaties into two layers
        • 4. Drying
          • Any remaining water in teh ethyl ethanoate can be removed by shaking it with lumps of anhyrous chloride, whihc absorbs water whihc is called drying
      • Fats and oils are esters of glycerol and fatty acids

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