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C8 Chemical Analysis

Last updated about 1 month ago
32 questions
4.8.1.1 Pure substances
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A pure substance has to be an element

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A mixture is always an impure substance.

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Impure substances have higher boiling points

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Salt is put on ice to increase the melting point.

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Identify 2 differences between pure and impure substances

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What happens to the melting point of water when impurities are added?

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Many people would say that spring water is pure. Is this a pure substance? Explain your answer.

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A student compared a sample of isooctane with some petrol. The student found that the octane boiled at 99°C while the petrol boiled between 45 and 95°C. Which of these is a pure substance? Explain your answer.

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Explain why salt is placed on roads in winter months?

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4.8.1.2 Formulations
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A green ink contains 85% yellow dye and 15% blue dye.
Determine the simplest whole number ratio of yellow dye : blue dye in the green ink.

Yellow dye : Blue dye =

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A fertiliser contains 0.225 g of iron per 3.0 g of fertiliser.

Which calculation gives the percentage of iron in the fertiliser?

Tick one

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Formulations have specific amounts of each chemical

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Diesel is a formulation. What is a formulation?

4.8.1.3 Chromatography
4.8.2 Identification of common gases
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Use the ruler tool on this chromatogram - you will need this to answer the next questions.

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How many substances are in dye A?

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How many substances are in Dye B?

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Calculate the Rf value for substance P

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Calculate the Rf value for substance Z

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Calculate the Rf value for substance Y

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Calculate the Rf value for substance X

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Explain how the chromatogram shows that A is a pure substance and B is a mixture.

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Why is the start line drawn in pencil rather than pen?

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In chromatography, ink is the solvent.

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In chromatography, the dyes are soluble in water.

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Chromatography allows us to separate different elements in a compound.

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Simple distillation allows us to separate liquids with different boiling points.

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What colours are in substance P?

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Put the order of Chromatography in order

  1. Draw a line with a pencil and ruler to one end of the strip of filter paper
  2. When the solvent has almost reached the top of the filter paper, remove it from the beaker
  3. Use a ruler to measure the distance the ink spot has travelled (Rf values)
  4. Place a spot of ink on the pencil line
  5. Suspend the filter paper in a beaker so it isn't touching the sides or the bottom
  6. Carefully add the solvent to a level just below the ink spot, taking care not to splash the paper
  7. Lay the paper flat and leave it to dry
  8. Cover the beaker and wait a few minutes
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Match the gas test to its positive result

Draggable itemCorresponding Item
Put Damp litmus paper into the gas
Limewater turns milky (cloudy)
Place a glowing splint in a test tube of the gas
Litmus paper is bleached and turns white
Hold a burning splint at the open end of a test tube of the gas
A squeaky pop sound is produced
Shakes or bubble the gas through limewater
The splint relights.
…
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This question is about gas tests - sort into Tests and Results

  • Litmus paper is bleached and turns white
  • Shakes or bubble the gas through limewater
  • A squeaky pop sound is produced
  • Put Damp litmus paper into the gas
  • Limewater turns milky (cloudy)
  • Hold a burning splint at the open end of a test tube of the gas
  • Place a glowing splint in a test tube of the gas
  • The splint relights
  • Test
  • Result
…
4.8.3.1 Flame Tests
4.8.3.2 Metal Hydroxides
4.8.3.3/4/5 Antions (Carbonate, Halide, Sulfate)
4.8.3.6 Instrumental Methods
4.8.3.7 Flame Emission Spectroscopy