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AQA Chemistry GCSE > Chemical Analysis > Flashcards

Chemical Analysis Flashcards

1
Q

How can you test for carbonates?

A

Dilute Acid.
- Using a pipette, add a few drops of dilute acid to the mystery substance.
- Connect this to a test tube containing limewater.
- If carbonate ions are present, the acid will produce carbon dioxide turning the limewater cloudy.

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2
Q

What happens to the limewater when dilute acid is added to a solution containing carbonate ions?

A

It turns cloudy.

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3
Q

What ions are in carbonates?

A

CO3 2-

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4
Q

How do you test for sulfates?

A

Barium Chloride.
- Using a pipette, add a couple drops of dilute hydrochloric acid followed by a few drops of barium chloride to the test tube containing the mystery substance.
- If sulfate ions are present, a white precipitate of barium sulfate will form.

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5
Q

Why is hydrochloric acid added with barium chloride when testing for sulfates?

A

To get rid of any traces of carbonate ions before testing as carbonate ions will also produce a precipitate, so they’d confuse the results.

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6
Q

How do you test for halides?

A
  • Add a couple drops of dilute nitric acid followed by a couple drops of silver nitrate solution.

Chloride ions - white precipitate (silver chloride)

Bromide ions - cream precipitate (silver bromide)

Iodide - yellow precipitate (silver iodide)

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7
Q

What is the ion formula for sulfate ions?

A

SO4 2-

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8
Q

What type of ions do flame tests, test for?

A

Cations.

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9
Q

What type of ions does dilute acid, barium chloride and silver nitrate solution test for?

A

Anions.

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10
Q

How does a flame test work?

A
  • Clean a nichrome or platinum wire loop by rubbing with fine emery paper, then hold it in the blue flame of a bunsen burner. The bunsen flame might change colour, but once its blue again, the loop is clean.
  • Dip the loop into the sample you want to test and then put it back into the bunsen flame. Record the colour of the flame.
  • Use the colours to detect and identify different ions.
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11
Q

What is a disadvantage of a flame test?

A

It only works for samples that contain a single metal ion.

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12
Q

Name the colour of the flame produced by the following metal ions:
Lithium, Sodium, Potassium, Calcium and Copper.

A

Lithium ions Li+ —> crimson
Sodium ions Na+ —> yellow
Potassium ions K+ —> lilac
Calcium ions Ca2+ —> orange-red
Copper ions Cu2+ —> green

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13
Q

What is a pure substance?

A

Something that only contains one compound or element throughout.

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14
Q

What tells you how pure a substance is?

A

The boiling or melting point

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15
Q

How can you test how pure a substance is?

A

Compare the boiling or melting point of a sample with the boiling or melting point of the pure substance. The closer the measure value is to the actual value, the purer your sample.

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16
Q

Complete the sentence : Impurities in a sample will _________ the melting point and ______________ the melting range of your substance.

A

lower, increase

17
Q

True or false : Impurities in your sample will increase the boiling point.

A

True

18
Q

What are formulations?

A

Mixtures with exact amounts of components.

19
Q

How are formulations made?

A

Following a formula/ recipe.

20
Q

What is an example of a formulation and what is it composed of?

A

Paints are composed of:
- pigment (colour)
- solvent (dissolves components & alters the viscosity)
- binder (forms a film that holds pigment in place)
- additives (further changes the physical and chemical properties)

21
Q

Why are formulations important in the pharmaceutical industry?

A

The formulation can make sure that the drug is delivered to the correct part of the body at the right concentration, that it’s consumable and has a long enough shelf life.

22
Q

Give 2 examples of formulations in everyday life.

A

Cleaning products, fuels, cosmetics, fertilisers, metal alloys and food & drink

23
Q

What is the test for chlorine?

A

Bleaches damp litmus paper (turns white) if present.

24
Q

What is the test for oxygen?

A

Glowing splint will relight if oxygen is present.

25
Q

What is the test for carbon dioxide?

A

If bubbled through an aqueous solution of calcium hydroxide (limewater), the solution turns clouds if carbon dioxide is present.

26
Q

What is the test for hydrogen?

A

If you hold a burning splint at the open end of a test tube a squeaky pop can be heard if hydrogen is present.

27
Q

What are the two phases of chromatography?

A

A mobile phase - The molecules can move, always a liquid or gas.
A stationary phase - The molecules can’t move, a solid or a thick liquid.

28
Q

What is chromatography?

A

An analytical method used to separate the substances in a mixture.

29
Q

What can chromatography be used for?

A

To identify the substances separated.

AQA Chemistry GCSE (9 decks)

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