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GCSE Chemistry Paper 2 > Chemical Analysis > Flashcards

Chemical Analysis Flashcards

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1
Q

What is a pure substance?

A

Something that only contains one compound or element

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2
Q

How can you test the purity of a substance?

A

Measure its melting and boiling points and compare this with the set boiling point of the pure substance. The closer it is to the pure substance, the purer it is.

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3
Q

What are formulations?

A

Useful mixtures with a precise purpose that are made by following a formula. Each component is present in a measured quantity to meet its required function.

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4
Q

What are some uses of formulations?

A

-making sure pills deliver drugs to the correct part of the body.
-cleaning products
- paint
-fuels
-cosmetics
-fertilisers

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5
Q

What are the two stages of chromatography?

A
  • Mobile phase - molecules can move (liquid or gas
  • Stationary phase - molecules can’t move (solid or really thick liquid)
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6
Q

What does the speed and separation of the chemical reaction depend on?

A

The distribution of substances between the two phases

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7
Q

What are the mobile and stationary phases of paper chromatography?

A

The chromatography paper is the stationary phase and the solvent is the mobile phase

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8
Q

What is the the Rf value?

A

The ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent. The further through the stationary phase a substance moves, the larger the Rf value is.

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9
Q

What is the formula for the Rf value for a chemical?

A

Rf = distance travelled by substance (B) / distance travelled by solvent (A)

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10
Q

How can you tests to see if a certain substance is present in a mixture?

A
  • do a chromatography test on the pure substance alongside the unknown mixture.
  • If the Rf values of the mixture and one of the spots in the mixture match, the substance may be present.
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11
Q

How can you test for chlorine?

A

Expose a piece of litmus paper to the gas. If chlorine is present it will turn white.

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12
Q

How can you test for oxygen?

A

Put a glowing splint inside the test tube. If oxygen is present in the tube the splint will relight.

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13
Q

How can you test for carbon dioxide?

A

Shaking carbon dioxide/bubbling it through with limewater (an aqueous solution of calcium hydroxide) will cause it to turn cloudy.

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14
Q

How can you test for hydrogen?

A

light a splint and hold it a t the opening of a test tube. It will make a squeaky pop sound if hydrogen is present.

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15
Q

How do you test whether a solution contains sulfate ions?

A

Put the mixture in a test tube and then drop in a few drops of dilute hydrochloric acid and a few drops of barium chloride solution. If there a sulfate ions, a white precipitate of barium sulfate will form.

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16
Q

How do you tests for halide ions?

A

Andd a few drops of dilute nitric acid as well as silver nitrate solution.
- a chloride gives a white precipitate of silver chloride
-a bromide gives a cream precipitate of silver bromide
-an iodide gives a yellow precipitate of silver iodide

17
Q

What is the process of using the flame tests to identify metal ions?

A

-clean a platinum wire loop in dilute HCl
-hold it in a blue bunsen burner flame until it burns without colour
- dip it in the sample you want to test
-put it back in the flame and record the colour that the flame burns

18
Q

What colour do Lithium ions burn during flame tests?

A

Crimson red

19
Q

What colour do Sodium ions burn during flame tests?

A

yellow

20
Q

What colour do Potassium ions burn during flame tests?

A

Lilac

21
Q

What colour do Calcium ions burn during flame tests?

A

Orange-Red

22
Q

What colour do Copper ions burn during flame tests?

A

Green

23
Q

What is the process of using the colour test to identify metal ions?

A
  • add a few drops of sodium hydroxide to the solution
  • if a metal ion is present you get a coloured insoluble hydroxide
24
Q

What colour do calcium ions turn the solution in a colour test?

A

White

25
Q

What colour do copper III ions turn the solution in a colour test?

A

Blue

26
Q

What colour do iron II ions turn the solution in a colour test?

A

Green

27
Q

What colour do Iron III ions turn the solution in a colour test?

A

Brown

28
Q

What colour do aluminium ions turn the solution in a colour test?

A

white at first but then turns colourless

29
Q

What colour do magnesium ions turn the solution in a colour test?

A

White

30
Q

How does flame emission spectroscopy work?

A
  • sample placed in a flame
  • as the ions heat up their electrons jump up an energy level and then jump back down, transferring light energy
  • line passes through spectroscope which can detect different wave lengths to produce a line spectrum
  • different ions produce different wavelengths of light
  • intensity of the spectrum indicates the concentration of that ion solution
31
Q

What are the advantage of using machines for instrumental analysis instead of conducting tests?

A
  • very sensitive (detects even tiny amounts of substances)
  • very fast and can be automated
  • very accurate

GCSE Chemistry Paper 2 (5 decks)

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