C3 (Part 2)

Analysis & synthesis
1. Titration Calculations
  1. Concentration is measured in grams per decimetre cubed (g/dm3), or moled per decimetre cubed (mol,dm3)
  2. If we know the mass or number of moles, in a given volume we can work out concentration
  3. If we know volume of a solution and concentration we can work out the mass or moles
2. Chemical Analysis
  1. Some just looks at whether it is just in a substance e.g. the ion tests
  2. Others look at how much, e.g. Gas Chromatography and Mass spectometry
3. Equilibrium
  1. equilibrium is when the rate of the forward reaction is equal to the rate of the backwards reaction
    1. The reaction still continues but the amount of products remains constant
  2. Only occurs in reversible reactions
  3. The amount of reactants and products in a reversible can be changed by shifting the equilibrium
    1. E.G. ICl +Cl2 --> ICl3
      1. When there is plenty of Cl2 gas, more ICl3 is made
      2. When there is less Cl2 gas, more ICl is made
    2. Change in pressure
    3. Change in Temp.
4. Haber Process
  1. Makes ammonia that can be used as;
    1. fertiliser
    2. Explosives
    3. Some cleaning fluids
  2. Passed over an iron catalyst, at 200 Atmospheres. and 450 oC
  3. N2 + 3H2 --> 2NH3 <--
  4. The yield is only about 15% as some of the ammonia breaks back down in to N2 and 3H2
    1. To try and limit this (the reverse reaction) the ammonia is cooled so it condenses, it can then be extracted
  5. Optimum Conditions
    1. Pressure - As the product have fewer molecules, a high pressure will give the highest amount of product
      1. However a high pressure means a high cost for equipment so it can withstand the pressure, and energy to compress the gas
        200 Atmospheres is a good medium
    2. Temp - the forward reaction is exothermic and so the lower the temp the better
      1. However the rate of reaction decreases as temp. decreases and the iron catalyst becomes ineffective
        450 oC is a good inbetween
Organic Chemistry
1. Alcohols
  1. Functional group = -O-H
  2. Uses of alcohols
    1. The smaller alcohols, Meth., Eth., Prop., react well with water to form neutral solutions
    2. Many organic substances dissolve in them and so they are useful solvents
    3. Ethanol is used in Alcoholic beverages
  3. It reacts with sodium to form Hydrogen gas - it reacts less vigorous than Sodium in water
  4. Alcohols can be oxidises by agents such as Potassium Diochromate - Oxidised Ethanol produces ethanoic acid; this is the main acid in vinegar
2. Carboxylic acids
  1. Functional group = -COOH
  2. They react with water to produce a solution less that pH 7
    1. They also don't fully ionise in water - this means carboxylic acids are weak acids
3. Esters
  1. Esters are Carboxylic acids reacted with an alcohol, in the presence of an acid catalyst
    1. They have the functional group is -COO-
      1. The H atom from the carboxylic acid is replaced with an alcohol
        E.G. --> CH3 COOCH2 CH3 - Ethyl Ethanoate
  2. Some smell nice and are used in fragrences
4. They can benefit society when ussed appropreately but can be harmful if abused
5. Biofuels offer an alternative to fossil fuels, but the plants they are grown from take up agriculteral land and so can cause food shortages

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C3 (Part 2)

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