Core Practicals

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  • Created by: EllenPlay
  • Created on: 27-05-18 11:59
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  • Core Practicals
    • Electrochemical cells
      • Ecell= Erhcell-Elhcell
      • Standard Conditions not maintained temparature not 298K not standard concetration 1moldm-3
      • slver nitrate is weekened as its highly oxidising and expensive
    • The oxidation of ethanol
      • Reflux and distillation
      • Acidified sodium dichromate highly oxidising
        • Gloves
      • Ph using indicator paper goes red
      • Forming a carboxylic acid
      • Calcium carbonate effervescence shows acid product ( gas turns lime water cloudy)
      • Magneesium followed by squeaky pop test (acid)
      • Fehlings solution no reaction means no aldehyde left
    • Determining Ka for a week acid
      • pH=-log[H+]
      • measurements with a pH meter calilbrated
      • Ka found by titrating known volume against NaOH using phenolphthalein, a further equal vol of acid added then pH measured
      • Uncertainty  inaccuracy of burette readings difficulty identifying end-point. Read from the bottom of the meniscus;  white tile can see colour change clearly.
      • Finds half equivalence point pH=pKa
    • The hydrolysis of halogenoalkanes
      • Rates of hydrolysis of Chloro-Bromo-Iodoalkanes
        • Also rates of primary secondary and tertiary
          • Secondary and tertiary faster rate
            • Less time to form a ppt
      • Further down the group = more reactive
        • Less time to form a ppt
      • Water in the presence of AgNo3
        • Nucleophillic Substitution
      • Halogeno- alkanes insoluble in water so ethanol ensures dissolves so it can then react
        • Water used instead of hydroxide as hydroxide would form silver hydroxide
    • Find the concentration of a solution of HCl
      • Phenolphthalein indicatior
        • End point when idicator goes pink
        • Pink colour may fade on standing as CO2 in the air neutralises any excess NaOH
      • Concordant results within o.02cm3 of each other
      • Using Standard NaOH solution
    • Rate of iodine propanone reaction. Titrimetric method
      • Continuous monitoring method
      • Concentration time graph
        • To determine order of reaction
      • Pippette 10cm3 samples
        • Add NaHCO3 to quench note time
          • Titrate remaining solution against Na2S2O8 with starch indicator
    • Activation energy bromide Vs bromste(V) ion reaction
      • time taken for a reaction to happen at different temperatures
      • Arrhenius equation
    • Chlorination f 2-methylpropan-2-ol
      • Producing a pure sample of 2-Chloro-2-methyl-propane
        • Add HCl in a conical flask then anhydrous calcium carbonate takes unreacted alcohol
          • Continually remove bung and release pressure whilst swirling
            • Transfer to separating funnel. Seperate layers formed by pouring off bottom layer/ decanting
              • Add sodium hydrogen arbonate to remove acid washing.
                • add anhydrous sodium sulfate drying agent
                  • Decant and distil between small range
      • Lower boliling point than reactant
        • Cannot form hydrogen bonds
    • Find the concentration of a solution of sodium hydroxide
      • Known concentration of acid titrated against sodium hydroxide
      • Dissolve known mass of salfamic acid into 250cm3 volumetric flask
      • Methyl orange indicator
    • Clock reaction rate equation
      • varying changes on peroxodisulfate and iodide ions
      • Rate vs Conc graph plotted
    • Enthalpy change for thermal decomposition of potassium hydrogencarbonate
      • Uses Hess's law cannot be measured directly
        • High reacting temperature means water no longer under standard conditions
        • High temp beraks down Na2CO3 the product
      • Using HCl in excess
      • Polystyrene cup to redduce temperature loss or gain improving accuracy
    • Preparing a transition metal complex
      • hydrated copper sulfate to tetraammine copper(ii) sulfate
      • React in ethanol and buchner funnel with cold ethanol
    • Iron in iron tablet, Redox titration
      • Iron Fe2+ against MnO4-
        • Colourless to pink
      • Crush tablet and react with H2SO4
        • Filter wash add to volumetric flask
          • Pipette titrate until just pink
    • Identifying unknowns
      • Potassium chromate oxidises
        • Orange to green
        • Aldehyde / alcohol
      • Silver Nitrate
        • Chloride / Bromide / Iodide
          • Precipitate white      cream    yellow
        • Nitric acid added
          • Destroys carbonate ions
      • Fehilings
        • Blue to red
          • Aldehyde
      • Bromine water
        • Decolourises
          • Alkene
      • Flame test
        • E=hf
          • Ba Green    Na Yellow       K Lilac            Li Red            Cu Green      Ca Red          Sr Red            Mg Be N/A
      • Chlorine water
        • Decolourise
          • Shows bromine ion
      • Barium Chloride
        • Insoluble ppt
          • Test for sulphate ion
            • BaSO3 dissoleves in excess HCl
      • Sodium hydroxide
        • Identifies metal ion colour ppt
          • In excess Cr redisolves
    • Measure the molar volume of a gas
      • Volume of 1mol gas
        • Gas collection in water with measuring cylinder
        • Collection with gas syringe
      • Physical divide between reactants before combining in tube
        • Error from not getting lid on in time
      • Cakcium calbonate vs volume produced graph
      • Ethanoic acid and Calcium carbonate
    • Synthesise aspirin
      • Reaction of ACID ANHYDRIDE
        • from 2-hydroxybenzoic acid
      • Warm using water bath
      • Add ice to break down unreacted anhydride
      • Form ppt then buchner funnel
        • wash crystals min amount of water
          • Filter and dry
      • Measure melting temp and range
        • impurities wet

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