Chemistry- Separating substances 0.0 / 5 ? ChemistrySeparating substancesIGCSECIE Created by: KitsuneCreated on: 28-06-16 19:02 What is a mixture? It contains more than one substance that are not chemically combined 1 of 37 What is a solute? Something that is dissolved 2 of 37 Why is the solubility of every substance different? Because all particles are different 3 of 37 What happens to solubility when temperature rises? It increases 4 of 37 What does saturated mean? A solution can't dissolve more solute at that temperature 5 of 37 What is a solution in water called? Aqueous solution 6 of 37 What does volatile mean? A liquid that evaporates easily 7 of 37 What does ethanol dissolve? Glues, printing inks 8 of 37 Why are some substances volatile? The forces between the particles are very weak 9 of 37 What is a pure substance? It doesn't have any other substances mixed with it 10 of 37 Why do some substances need to be pure? Impurities can be harmful to humans 11 of 37 Which substances need to be pure? Medical drugs and food flavourings 12 of 37 What is an impurity? An unwanted substance mixed with the substance you want 13 of 37 How to check for purity? Check melting and boiling points because a pure substance has a sharp definite pair of them 14 of 37 What happens when an impurity is present? The melting point falls and the boiling point rises; melting and boiling occurs over a range of temperatures 15 of 37 What is used to separate an insoluble solid from a liquid? Filtration 16 of 37 What is the trapped solid in filtration? Residue 17 of 37 What is the clear liquid from filtration called? Filtrate 18 of 37 What is used to separate a soluble solid from a liquid? Crystallisation or evaporation of the solvent 19 of 37 Why is evaporation of the solvent used instead of crystallisation? For some substances solubility changes very little so there is no point is crystallisation 20 of 37 How to separate two solids in a mixture? Choose a solvent that dissolves only one of them and remove the other by filtration 21 of 37 What is used to separate a solvent from a mixture? Simple distillation 22 of 37 What is the point of a condenser? To help vapour condense 23 of 37 What is used to separate a mixture of gases? Fractional distillation 24 of 37 Why does fractional distillation work? It takes advantage of the different boiling points 25 of 37 What do the vapours in fractional distillation go through before they reach the condenser? Glass beads 26 of 37 Where is fractional distillation used? In petroleum industry to refine crude oil, in production of ethanol, to separate the gases in air 27 of 37 What is used to separate pigments and amino acids? Paper chromatography 28 of 37 Why do the substances in paper chromatography separate? They have different solubility 29 of 37 What does the solubility depend on in paper chromatography? The paper and the solvent 30 of 37 Which substance will travel further on the chromatogram? The most soluble one 31 of 37 What is paper chromatography used for? Identification/separation/purification of substances, checking purity, detective work 32 of 37 What is the solvent for amino acids? Water+ethanoic acid+butanol 33 of 37 What is used to make amino acids visible? Locating or fixating agent 34 of 37 How to find the Rf value? Distance moved by substance divided by distance moved by solvent 35 of 37 What is the Rf value for the same substance? It is the same under the same conditions and the same solvent 36 of 37 What two phases are there in chromatography? Stationary and mobile 37 of 37
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