Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > Booklet 8 - Purity, Formulations And Chromatography > Flashcards

Booklet 8 - Purity, Formulations And Chromatography Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

What is a pure substance in chemistry?

A

A pure susbatnce is a single element or compound, thats not mixed with any other substance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How can you test for the boiling and melting points of pure substances?

A

Pure substances melt or boil at specific temperatures
- melting and boiling points data can be distinguished pure substances from mixtures by testing the melting and boiling points of a substance and comparing it with the melting and boiling points of a pure substance, which you can find from the data book

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you know if a sample is pure?

A

The closer the measured value if the substance is to the actual melting or boiling points the purer the sample is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What two things can impurities in a sample do?

A

1) . Lower the melting point and increase the melting range of the substance
2) . May also increase the boiling point and may result in the sample boiling at a range of temperatures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a pure substance in a everyday language?

A

It can mean a substance that has had nothing added to it, so it is unadulterated and in its natural state eg pure milk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a formulation?

A

A mixture that has been designed as a useful product

- many products are complex mixtures in which each chemical has a particular purpose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How are formulations made?

A

They’re made by mixing the components in carefully measured quantities to ensure that the product has the required properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are some of the examples of formulations?

A

Fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is chromatography?

A

Can be used to separate mixtures and can give information to help identify substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What’s the mobile phase?

A

Where the molecules can move, always a liquid or a gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the stationary phase?

A

Where the molecules cant move, can be a solid or really thick liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does separation depend on?

A

the distribution of substances between the two phases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the process of chromatography?

A

1) . Draw a pencil line on the paper near the bottem using a ruler, pencil is used as ink would run
2) . Spot samples carefully onto the pencil line
3) . Hang in a beaker of solvent, ensuring that the pencil line is above the level of the solvent
4) . Close the lid and allow the solvent to rise up the paper
5) . When near the top, remove the paper and quickly mark with pencil where the solvent reached. This is the solvent front
6) . Allow paper to dry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does the mobile stage move through?

A

The stationary stage, and anything dissolved in the mobile phase moves with it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens to chemicals that spend more time in the mobile phase than the stationary phase?

A

They’ll move futher in the stationary phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What roles do the stationary and mobile phases play in paper chromatography?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Who two things do molecules depend on regarding how much time they spend in a phase in chromatography?

A

1) . How soluble they are in the solvent

2) . How attracted they are to the paper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens to molecules with a high solubility in solvent (chromatography)?

A

They are also less attracted to the paper and will spend more time in the mobile phase and they’ll be carried futher up the paper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How can the ratio of the distance moved by a compound to the distance moved by the solvent be expressed?

A

As its Rr value

Rr = distance moved by substance ➗distance moved by solvent

20
Q

What do different compounds have? (Chromatography)

A

They have different Rr values in different solvents, which can be used to help identify the compounds.

21
Q

Why may compounds in a mixture separate into different spots?

A

It depends on the solvent BUT a pure compound will produce a single spot in all solvents

22
Q

What is the test for hydrogen?

A

It uses a burning splint held at the open end of a test tube of the gad, the hydorgen burns rapidly with a pop sound

23
Q

What is the test for oxygen?

A

Uses a glowing splint inserted into a test tube of a gas, the splint relights in oxygen

24
Q

What is the test for carbon dioxide?

A

Uses an aqueous solution of calcium hydroxide (limewater), when CO2 is shaken with or bubbled through limewater, the limewater turns milky (cloudy)

25
Q

What is the test for chlorine?

A

Uses litmus paper, when it is damp it is put into chlorine gas and the litmus paper is bleached and turns white

26
Q

What are flame tests used for?

A

To identify some metal ions (cations), they all produce distinctive colours

27
Q

What colour do lithium ions burn?

A

Crimson red flame

28
Q

What colour do sodium ions burn?

A

A yellow flame

29
Q

What colour do potassium ions burn?

A

A lilac flame

30
Q

What colour do calcium ions burn?

A

A orange-red flame

31
Q

What colour do copper ions burn?

A

A green flame

32
Q

What is a drawback of the flame test technique?

A

If a sample contains a mixture of ions some of the flame colurs can be masked and therfore may not be noted

33
Q

What solution can be added to indentify metal ions (cations)?

A

Sodium hydroxide solution

34
Q

What colour precipitates do solutions of aluminium, calcium and magnesium ions form?

A

White precipitate when sodium hydroxide solution is added

35
Q

What precipitate dissolves in excess sodium hydroxide solution?

A

Aluminium hydroxide precipitate

36
Q

What ions form coloured precipitates when sodium hydroxide solution is added to it?

A

Solutions of copper (II), iron (II) and iron (III)

37
Q

What colour precipitates do copper (II), iron (II) and iron (III) form?

A
  • copper (II) forms a blue precipitate
  • iron (II) forms a green precipitate
  • iron (III) forms a brown precipitate
38
Q

How do you test for carbonate ions in solution?

A

By reacting them with dilute acids to form carbon dioxide gas which can be identified with limewater test

39
Q

How do you test for halide ions in solution?

A

Add dilute nitric acid followed by silver nitrate solution

40
Q

What colours chloride, bromide and iodide go in the prescene of dilute nitric acid and silver nitrate solution?

A
  • Chloride gives a white precipitate of silver chloride
  • bromide gives a cream precipitate of silver bromide
  • iodide gives a yellow precipitate of silver iodide
41
Q

How do you test for sulfate ions?

A

Add dilute hydrochloric acid followed by barium chloride solution. If they’re present a white precipitate of barium sulfate will form

42
Q

What are instrumental methods?

A

Elements and compounds can be detected and identified using imstrumental methods which are accurate, sensitive and rapid

43
Q

What are the advantages of standard lab testing and instrumental methods?

A
  • standard laboratory testing
    1) its available in school
  • instrumental methods
    1) very accurate
    2) sensitive and rapid
    3) only small amount of sample needed
44
Q

What is flame emission spectroscopy?

A

An example of instrumental method used to analyse metal ions in solutions

45
Q

How does flame emission spectroscopy work?

A

The sample is put into a foame and the light given out is passed through a spectroscope.
- the output is a line spectrum that can be analysed to identify the metal ions in the solution and measure their concentrations

46
Q

What do different ions have different line spectrums?

A

Different ions will emit different wavelengths so each ion produces a different pattern of wavelength therefore different line spectrum

47
Q

What does the intensity of the spectrum indicate?

A

The concentrations of that ion in the solution

Chemistry (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions