Analysis and Synthesis

This is about analysis of substances, the Haber Process, titrations, and other chemistry things.

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  • Created by: Lizzi
  • Created on: 28-04-13 17:55
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  • Analysis and Synthesis
    • Tests for positive ions
      • Most group 1 & 2 metals can be identified by flame tests
        • Litium (Li+) = Crimson/ red
        • Sodium (Na+) = yellow
        • Potassium (K+) = lilac
        • Calcium (Ca2+) = red
        • Barium (Ba2+) = green
      • Sodium hydroxide solution can be used to identify different metal ions, depending on the precipitate it produces
        • Aluminium, Calcium, and Magnesium = white
        • Copper (II) Hydroxide = blue
        • Iron (II) Hydroxide = green
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    • Tests for negative ions
      • Carbonates are identified by adding dilute acid. This produces CO2, which turns limewater cloudy.
      • We identify halides by adding nitric acid; it produces silver halide.
        • Chloride = white
        • Bromide = cream
        • Iodide = pale yellow
      • We identify sulfates by adding hydrochloric acid and barium solution, which produces barium sulfate.
    • Titrations
      • A titration is used to measure how much acid and alkali react together completely
      • The point at which an acid-base reaction is complete is called the End Point.
      • An indicator is used to show when the end point.
      • Concentration is measured in g/dmcubed or mol/dmcubed
      • Conc. can be calculated by the mass of a solute in a known solution volume (and vice versa)
      • If the conc. of one solution is known, the results of the titration can be used to calculate the conc. of the other solution.
    • Chemical analysis
      • Scientists working in environmental monitoring, medecine, and forensics need to analyse substances.
      • The results are usually matched against existing data to identify substances/ suspects.
    • Chemical equilibrium
      • In a reversible reaction, the products can re-react to form the original reactants.
      • In a closed system, equilibrium is achieved when the rates of the forward and reverse reaction are equal.
      • Changing the conditions can alter the amount of products and reactant.
    • Altering Conditions
      • Changing the pressure can affect a reversible reactions involving gases at equilibrium
        • Increasing favours the side with the smaller number of gas molecules formed.
        • Decreasing favours the side with less gas molecules.
      • Changing the temp. will vary the amount of products formed at equilibrium.
        • Increasing temp. favours endothermic reaction
        • Decreasing temp. favours endothermic reaction.
    • Haber Process
      • Ammonia is an important chemical that makes things like fertilisers
      • It's made from nitrogen and hydrogen.
      • Haber Process is done using conditions chosen to give a reasonable yield of ammonia as quickly as possible
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      • The economics of the Haber Process
        • It uses pressure of about 200 atmospheres,to increase ammonia production.
        • Although higher pressure creates more ammonia, less is used as more would be too expensive.
        • A temperature of 450 degrees C is used.
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