C2.1

    Cards (83)

    • Relative atomic mass
      Relative atomic mass, Ar, is the mean mass of an atom of an element compared to 1/12 the mass of a carbon-12 atom
    • Why may Ar be in decimals?
      It is an average therefore takes into account all the isotopes
    • Where can you find all the relative atomic masses of elements?
      The Period Table
    • Relative formula mass
      Relative formula mass, Ar, is the mean mass of an atom of a substance compared to 1/12 the mass of a carbon-12 atom
    • How to solve relative formula mass?
      Find the relative atomic mass of each seperate element and add them up
    • Is there a units for relative formula and atomic mass?

      No just a number
    • What is an empirical formula?
      An empirical formula shows the simplest whole-number ratio of the atoms of each element in a compound
    • What is a molecular formula?
      The unsimplified formula of a molecule
    • How to find the empirical formula from percentages?
      Write the percentages and their atomic mass. Divide the percentage by the atomic mass. The lowest of all of these number you should divide this number by the others. The data you have recieved is the number of that element in the compound e.g
      74.2% sodium - 74.2 / 23 = 3.23/1.16 = 2
      25.8% oxygen - 25.8 / 16 = 1.16/1.16 = 1
      Empirical formula is Na2O
    • How to find the empirical formula given the mass?
      Write the mass and atomic number down. Divide the mass by the atomic number. The lowest of these number should divide the others to get a value. These values show the amount of atoms in one molecule of that substance
    • Can one element have 1.5 when in empirical form?
      No it has to be a whole number therefore all other number will need to double to allow the 1.5 to become a 3, a whole number
    • Solute
      A substance that is dissolved in a solution.
    • Solvent
      the substance in which the solute dissolves
    • Dissolving
      when the solute particles are wraped in the solvent particles and go into an irregular arrangment.
    • Insoluble
      can't dissolve
    • Soluble
      can dissolve
    • Miscible
      Describes two liquids that are soluble in each other
    • Immiscible
      liquids that are not soluble in each other
    • What is filtration?

      Method to separate an insoluble substance from a solvent
    • Desribe the apparatus used for filtration
      Beaker
      Filter funnel
      Filter paper

      Filter paper placed in the funnel in a cone shape which is place above the beaker to allow the liquid to fall into it.
    • Why is filter paper used?
      Filter paper has tiny holes in it to allow liquids such as water to pass through but solids such as sand to be left behind. It is folded into a cone.
    • What is the name of the substance left behind in to the filter paper?
      Residue
    • What is the name of the substance that passes through the filter paper?
      Filtrate
    • Will the filtrate always be pure?
      No it could be a solution such as salt and water which can pass through the filter paper
    • What is evaporation/crystallisation?

      Method to separate a soluble solid from a solution
    • Describe the apparatus used in crystallisation?
      Bunson Burner
      Tripod
      Gauze
      Evaporating basin
      Heat mat

      Tripod is placed over the bunson burner, which is placed on top of the heat mat,with a gauze on it and evaporating basin
    • How to obtain crystals?

      In order to form crystals slowly heat the mixture until it is saturated. Then let is evaporate naturally until crystals have formed
    • Pure substance
      Contains only 1 type of compound/elements
    • Formulations
      Mixtures that have been prepared using a specific formula which can be shown in ratios e.g. green paint
    • What are the 2 types of distillation?
      Simple distillation and fractional distillation
    • Simple distillation
      Method for obtaining a solvent from a solution. Solution can be solute and solvent or solvent and solvent
    • What do the boiling points of the substances in distilllation need to be?
      The need to be far apart to prevent both being boiled and condensed
    • Describe the apparatus used in simple distillation
      Bunson burner
      Round-bottom flask with bung
      Condenser
      Beak
      Thermometer
      Water source and tubes

      Round-bottom flask placed above the bunson burner with a bung and thermometer attatch to it. The round bottom flask connect to the condenser with streams of water entering and leaving. The condenser leads into a beaker
    • What is the role of the condenser?
      The condenser has a stream of cold water entering and leaving to allow the gas form of a substance to cool down and condense and drop into the beaker as a distillate
    • Describe how distillation takes place?
      The solution is heated and boils the solvent (lowest boiling point). The gas rises and enters the condenser where it cools down and turn into a liquid. It then enters the beaker as a distillate.
    • Fractional distillation
      Method of separating mixtures of 2 or more liquids.
    • Describe the apparatus used in fractional distillation?
      Round bottom flask with bung
      Buson burner
      Conndenser
      Thermometer
      Fractionating column
      Beaker

      The round bottom flask placed over the bunson burner with a fractionating column attached to it. The thermometer and bung as placed at the top of the column. The condenser is joined with the fractionating column with streams of water going in and out. The condenser leads to a beaker which holds the distillate
    • What is the role of the fractionating column?
      The fractionating column helps prevents solvents that are not wanting to be seperated to be separated. It contains many small glass rods. As the first solvent in gas form rises the the top the fractionating column heats up the that temperature. If any other solvents evaporate they will condense and sink down due to the temperature
    • What is the name of the substance collected at the end of distillation?
      Distillate
    • How does fractional distillation work?
      Solution is heated and the solvent with the lowest boiling point
      As it rises it heats up the fractionating column to prevent other solvents from
      It will then condense in the condenser and drip into the beaker
      Other solvents may evaporate but will condense again due to the fractionating column
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