Chemical Analysis Flashcards

1
Q

What is chromatography used for?

A

Separate mixtures (mainly inks and dyes) of coloured and non-coloured substances that are soluble in the same solvent

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2
Q

What are the 2 phases of chromatography?

A

Mobile and stationary

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3
Q

What does Rf stand for?

A

Retention factor

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4
Q

What is the equation for work out the Rf value?

A

Rf = distance moved by substance / distance moved by solvent

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5
Q

What is a pure substance?

A

A substance that is made up of only one type of element or compound

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6
Q

What is a mixture?

A

Two or more substance that aren’t chemically bonded together

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7
Q

How can you tell if a substance is pure from a graph?

A

The boiling point is sharp and at a specific temperature

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8
Q

How can you tell if a substance is impure from a graph?

A

The boiling point is a range

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9
Q

What is a formulation?

A

A mixture that’s been designed to produce a useful producr

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10
Q

Examples of formulations

A

Perfume, medicinal drugs, paint, fuels

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11
Q

What happens if a substance has a greater attraction to the mobile phase?

A

It moves a greater distance

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12
Q

What happens if a substance has a greater attraction to the stationary phase?

A

Won’t travel as far

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13
Q

How do you test for hydrogen?

A

Collect the gas, light a split, put fire in test tube

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14
Q

What will happen if hydrogen is present?

A

A squeaky pop sound is made

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15
Q

How do you test for oxygen?

A

Light a wooden split, blow it out until it’s glowing, put it in the gas

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16
Q

What will happen if oxygen present?

A

The splint will relight

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17
Q

How do you test for carbon dioxide?

A

Bubble the gas through limewater

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18
Q

What will happen if carbon dioxide is present?

A

The limewater will go milky/cloudy

19
Q

How do you test for chlorine?

A

Put damp litmus paper near gas

20
Q

What will happen if chlorine is present?

A

The litmus paper will turn white

21
Q

How are positive ions formed?

A

When an atom loses electrons

22
Q

Examples of positive ions

A

Potassium and Lithium

23
Q

How do you carry out the flame test?

A
  1. Dip a nichrome wire loop into HCl and sterilise it then dip it in HCl again
  2. Dip the loop into the metal compound being tested
  3. Hold the loop in a blue flame of a bunsen burner
  4. Use the colour of the bunsen burner to identify the metal ion
24
Q

What colour does Lithium turn during the flame test?

A

Crimson

25
Q

What colour does Sodium turn during the flame test?

A

Yellow

26
Q

What colour does Potassium turn during the flame test?

A

Lilac

27
Q

What colour does Calcium turn during the flame test?

A

Orange/Red

28
Q

What colour does Copper turn during the flame test?

A

Green

29
Q

What metals form a white precipitate during the sodium hydroxide test?

A

Aluminium, Magnesium, Calcium

30
Q

What metal form a blue precipitate during the sodium hydroxide test?

A

Copper

31
Q

What metal form a iron(II) precipitate during the sodium hydroxide test?

A

Green

32
Q

What metal form a iron(III) precipitate during the sodium hydroxide test?

A

Brown

33
Q

What happens if you add more sodium hydroxide to the precipitate formed by aluminium ions?

A

It dissolves

34
Q

What is the test for carbonates?

A

Adding a dilute acid to the metal being tested

35
Q

How do you know if a carbonate is present?

A

Carbon dioxide is formed

36
Q

What are halides?

A

Chlorides, bromides and iodides

37
Q

How do you test for halides?

A

Add dilute nitric acid and silver nitrate to a the halide and allow a precipitate to form

38
Q

What colour precipitates do different halides form?

A

Iodide ions - yellow
Bromide ions - cream
Chloride ions - white

39
Q

How do you test for sulphates?

A

Add HCl and barium chloride the sulphate ion sample

40
Q

How do you know if a sulphate is present?

A

A white precipitate is formed

41
Q

What are advantages of instrumental analysis?

A

Accurate, quick, sensitive, can detect small amounts

42
Q

What are disadvantages of instrumental analysis?

A

Expensive, special training needed

43
Q

What is flame emission spectroscopy used for?

A

Analysing samples of metal ions

44
Q

How does flame emission spectroscopy work?

A

In the spectrometer, wavelengths of light are provided to be analysed. Each type of ion emits and absorbs it’s own characteristic pattern of radiation, this is called the line spectrum and it can be used to identify metal ions