Topic 8- Chemical Analysis

  • Created by: Aimee978
  • Created on: 19-10-17 17:14
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      • A pure substance is made with only one element or compound
        • The boiling/melting point can help you to tell how pure a substance is
        • A pure substance will melt/boil at one temperature
          • The boiling/melting point can help you to tell how pure a substance is
          • Impurities will lower the melting/boiling points and increase the range of points
        • A formulation is a useful mixture with a precise purpose, made by following a formula
          • Formulations include ingredients such as: Pigment, solvent, binder and additives
            • Pigment for colour
            • Additives to change taste + other physical/chemical properties
            • Binder to stick and hold everything together
          • In everyday life these are things like: Cosmetics, medicine, cleaning products etc.
        • Chromatography is used to separate substances in a mixture
          • Molecules wit higher solubility and which are less attracted to the paper will travel further
            • Molecules with lower solubility and which are more attracted to the paper will travel less
        • We calculate Rf values for each chemical in a chromatograms
          • Calculating the Rf value: Distance travelled by the substance / distance travelled by the solvent
        • Chlorine: bleaches damp litmus paper white
          • The paper may turn red at first because Chlorine has an acidic Ph
        • Oxygen: Relights a glowing splint
        • Carbon Dioxide: Bubbling C02 through limewater (calcium hydroxide) should turn the solution cloudy
        • Hydrogen: Holding a lit splint over a test tube containing Hydrogen should produce a squeaky pop
          • The noise is because the Hydrogen burns quickly with the Oxygen to form H20


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