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Chemistry > C12-Paper 2 > Flashcards

C12-Paper 2 Flashcards

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1
Q

What is the formula for retention factor?

A

distance moved by substance/distance moved by solvent

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2
Q

What is a retention factor?

A

The ratio of the distance the spot moved above the origin to the distance the solvent front moved above the origin.

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3
Q

What is the definition of a pure substance?

A

Made up of just one substance. That substance can either be an element or a compound.

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4
Q

Describe the ‘fixed points’ of pure substances?

A

Melting and boiling point, a set temperature.

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5
Q

What is the melting point of pure water?

A

0 degrees

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6
Q

What is the boiling point of pure water?

A

100 degrees

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7
Q

Where are the fixed points stored?

A

Databases and databooks

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8
Q

What is the melting and boiling point like for an impure substance (a mixture)?

A

Carries out over a range instead of a specific temperature.

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9
Q

Impurities tend to do what to the melting and boiling point?

A

Lower the melting, raise the boiling point.

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10
Q

What is a formulation?

A

A mixture that has been designed to produce a useful product.

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11
Q

Give some examples of formulations?

A

Medicinal drugs, paint, cleaning agents, fuel, cosmetic products ect.

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12
Q

What is a technique used to identify unknown compounds in substances like ink?

A

Paper chromotography

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13
Q

Give an example of how paper chromatography can be used to separate and identify substances in a mixture:

A

Separating mixtures of amino acids, ink in a pen.

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14
Q

What is the mobile phase in paper chromatography?

A

The solvent chosen.

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15
Q

What is a mobile phase (definition)?

A

Moves through the stationary phase, carrying the components of the mixture under investigation with it.

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16
Q

What is the stationary phase of paper chromatography?

A

The paper.

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17
Q

What do we call a complete paper chromatography sheet?

A

Chromatogram.

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18
Q

What is the test for hydrogen?

A

Positive test for hydrogen: a lighted splint ‘pops’.

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19
Q

What is the test for oxygen?

A

Positive for oxygen gas: a glowing splint relights.

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20
Q

What is the test for carbon dioxide?

A

Positive test for carbon dioxide gas: limewater turns milky (cloudy white).

21
Q

What is the test for chlorine?

A

Positive for chlorine gas: damp blue litmus paper turns white (as it gets bleached).

22
Q

What flame colour does lithium produce?

A

Crimson.

23
Q

What flame colour does sodium produce?

A

Yellow.

24
Q

What flame colour does potassium produce?

A

Lilac.

25
Q

What flame colour does calcium produce?

A

Orange-red.

26
Q

What flame colour does copper produce?

A

Green.

27
Q

What type of materials does a flame test test for?

A

Positive ions (metals).

28
Q

The process of a flame test:

A

-A nichrome wire loop should be dipped in concentrated hydrochloric acid and then heated to clean it first. Then it should be dipped in the acid again before dipping it into the metal compound that is being tested.
-Then hold the loop in the roaring blue flame of a Bunsen burner.
-Use the colour of the Bunsen flame to identify the metal ion in the compound.
-However, if the sample being tested contains a mixture of metal ions, then some flame colours can be masked. For example, the intense yellow colour of sodium ions can dominate other colours.

29
Q

What is another way to identify positive ions (not flame testing)

A

Adding sodium hydroxide solution.

30
Q

What ion forms a reddish-brown precipitate when mixed with sodium hydroxide solution?

A

Iron(III)

31
Q

What ion forms a light blue precipitate when mixed with sodium hydroxide solution?

A

Copper

32
Q

What ion forms a light green precipitate that turns murky brown when mixed with sodium hydroxide solution?

A

Iron(II)

33
Q

Which two ions create a white precipitate that is insoluble in excess sodium hydroxide solution?

A

Magnesium and calcium.

34
Q

What ion forms a white precipitate that dissolves in excess sodium hydroxide solution?

A

Aluminium

35
Q

How can we test for carbonates?

A

Adding a dilute acid to a carbonate produces carbon dioxide. It fizzes.

36
Q

What are the three different halides we can test for?

A

Chlorides, Bromides, Iodides.

37
Q

How do we test for halides?

A

Add dilute nitric acid and then silver nitrate solution. If a precipitate forms, there are halide ions present.

38
Q

What colour precipitate does an iodide ion give?

A

Yellow (butter)

39
Q

What colour precipitate does a bromide ion give?

A

Cream (cream)

40
Q

What colour precipitate does a chloride ion give?

A

White (milk)

41
Q

How can we test for sulfates?

A

Adding dilute hydrochloric acid, followed by barium chloride solution. A white precipitate tells us that sulfate ions are present.

42
Q

Why do we add hydrochloric acids first to test for a sulfate ion?

A

To remove the carbonate ions that would form a precipitate with the barium ions.

43
Q

What do instrumental methods help with?

A

Accurate analysis of products, checking emissions produced.

44
Q

Give the 3 advantages of instrumental methods:

A

-Highly accurate and sensitive
-Quicker
-Enable very small samples to be analysed.

45
Q

Give the 3 disadvantages of using instrumental analysis:

A

-Very expensive
-Takes special training to use
-Gives results that can often be interpreted only by comparison with data from known substances.

46
Q

What does flame emission spectroscopy help to analyse?

A

Metal ions.

47
Q

How is flame emission spectroscopy presented?

A

Characteristic line spectrum.

48
Q

Describe the process of flame emission spectroscopy:

A

-The sample is heated in a flame
-The energy provided excites electrons in the metal ions, making them jump into higher energy shells.
-When they fall back to lower energy shells, the leftover energy is released as light energy.
-In the spectrometer, the wavelengths of the light produced can be analysed by passing it through a spectroscope.
-Each type of metal has its own pattern of radiation that can be recognised.

49
Q

How the concentration of the metal ions present in a sample for flame emission spectroscopy be determined?

A

The spectrometer can measure the intensity of light with a specific wavelength.

Chemistry (2 decks)

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