Double Award and Chemistry GCSE
54) What are the 3 states of matter?
Answer 54 Solids, liquids and gases.
55)
Name the interconversion between the:
- Solid to the liquid state
- Liquid to the gaseous state
- gaseous state to the liquid state
- Liquid to the solid state
- Melting
- Evaporating (or if heated to boiling point – Boiling)
- Condensing
- Freezing
56)Describe how the particles arrangement, movement and energy changes during melting.
Answer 56 The particles energy increases on heating causing the vibrations between particles to increase to an extent that they break free from their regular arrangement and start moving over one another.
57) Describe how the particles arrangement, movement and energy changes during condensing.
Answer 57 The particles energy decreases on cooling causing the particles to slow down and become attracted to other particles.
58)What is the difference between a pure substance and a mixture?
Answer 58 A pure substance is made of just one thing whereas a mixture is made of more than one substance which are not chemically joined.
59) What type of mixtures can be separated by each of these techniques?
- Simple distillation
- Fractional distillation
- Filtration
- Crystallisation
- Paper chromatography
- A dissolved solid where you want to keep the liquid or 2 liquids with very different boiling points.
- A large sample of a mixture of liquids with similar boiling points
- An insoluble solid and a liquid.
- A dissolved solid where you do not want the liquid.
- A small sample of a mixture of liquids.
60) What is Chromatography?
Answer 60 A separating technique used to separate mixtures of soluble substances by running a solvent (mobile phase) through the mixture on the paper (stationary phase) which causes the substances to move at different rates over the paper.
61)How can you use paper chromatography to identify a substance?
Answer 61 Each substance will run a specific distance up the paper and have its own unique Rf.
62) In chromatography, define the Rf value.
Answer 62
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63) How can ground water be made potable?
Answer 63 Sedimentation, filtration and chlorination.
64)How can sea water be made potable?
Answer 64 Distillation.
65) Why must water used in analysis not contain any dissolved salts?
Answer 65 Dissolved salts could cause an analysis to give a false positive result. In other words you might get a positive result for something that isn’t really there..