Topic 8-Chemical Analysis

Front 1

What is a pure substance made of

Back 1

It's only made up of 1 element or 1 compound

Front 2

What is an impure substance made of?

Back 2

A mixture of elements or a mixture of compounds

Front 3

A pure substance has a fixed...?

Back 3

Has a fixed melting and boiling point

Front 4

An impure substance has...

Back 4

A range of melting and boiling points

Front 5

What does a fixed melting and boiling point look like on a graph?

Back 5

F

Front 6

What does a range of melting and boiling points look like on a graph?

Back 6

F

Front 7

What is formulation?

Back 7

Is a complex mixture used to make a useful product e.g fuels and medicines.

Front 8

What is chromatography?

Back 8

It is a type of physical separation used by scientists.

Hint 8

Separate

Front 9

Paper chromatography is a physical process. What does that mean?

Back 9

It means that no chemical reactions occur and no new substances are made.

Front 10

What is the use for the paper chromatography experiment?

Back 10

Allows us to separate substances based on their different solubilities.

Front 11

How do we carry out the easy paper chromatography experiment?

Back 11

Firstly we take a piece of chromatography paper and draw a pencil line near the bottom.we then put a dot of our first colour and then put a dot of our second different colour next to it. We can do this for many colours as long as theres space on the paper.We then place the bottom of the paper into a solvent.(A solvent dissolves substances.) solvent then makes his way up the paper dissolving the ink of the coloured dots in the process. (Key facts: We call the paper the stationary phase because it does not move and we call the solvent the mobile phase because it does move.)

Front 12

What does the result of a single coloured spot mean in the chromatography experiment?

Back 12

It means that dot is a pure substance (only made up of 1 substance)

Front 13

What does the result of 2 separated coloured spots mean in the chromatography experiment?

Back 13

It means the 2 spots are impure substances because it's made from a mixture of substances.

Front 14

Why do we draw our line in pencil in paper chromatography

Back 14

Because if we drew a line in pen the ink would move up the paper with the solvent.

Front 15

How do we carry out the complicated paper chromatography experiment?

Back 15

We must first draw with a pencil,a horizontal line 2 cm above the bottom of the chromatography paper. Then draw small vertical lines every 1cm along the horizontal pencil line. Then with a thin glass tube, put a small drop of food dye onto each vertical line. Make sure the chromatography paper is hanging of a rod then place it into a beaker filled with a solvent (water) and put the lid on. There are 3 key facts to this experiment:

.The sides of the chromatography paper should not be touching the beaker or else it can impact the movement of the solvent

.Make sure a lid is on top of the beaker

.make sure the food dye dots and the horizontal pencil line are above the solvent or the ink will be mixed with the solvent

Front 16

I

Back 16

I

Front 17

I

Back 17

I

Front 18

How do we test for hydrogen?

Back 18

Remove the bung from the delivery tube and insert a burning splint. Hydrogen burns rapidly so if you hear a pop sound then hydrogen is present.

Front 19

How do we test for oxygen?

Back 19

Remove bung and insert glowing splint in delivery tube. If the splint relights then oxygen is present.

Front 20

How do you test for carbon dioxide

Back 20

You must have 2 test tubes: 1 with carbon dioxide and 1 with limewater(limewater is an aqueous solution of calcium hydroxide) Firstly take some carbon dioxide with a plastic pipette and then squeeze it into the limewater. After repeating this a few times if the limewater turns cloudy then carbon dioxide is present.

Front 21

How do we test for chlorine?

Back 21

Put litmus paper into the mouth of the test tube if a bit of the litmus get bleached/turns white, then chlorine is present.

Front 22

How do we carry out the flame test

Back 22

We put a bit of chemical onto a wir attached to a handle and put it under a Bunsen burner flame. The colour of the flame can tell us the metal ion present.

Front 23

A lithium ion produces a...

Back 23

Crimson flame

Front 24

A sodium ion produces a...

Back 24

Yellow flame

Front 25

A potassium ion produces a...

Back 25

Lilac flame

Front 26

A calcium ion produces a...

Back 26

Orange-red flame

Front 27

A copper ion produces a...

Back 27

Green flame

Front 28

What are the 2 problems with flame tests?

Back 28

.The colour of the flame can be difficult to distinguish especially if a low concentration of a metal compound is used.

.Sometimes the sample contains a mixture of metal ions which can mask the colour of the flame.

Front 29

How do you carry out flame emission spectroscopy?

Back 29

A sample of a metal ion in solution is placed into a flame. The spectroscope converts the light into a line spectrum. And the positions of the lines in the spectrum are specific for a given metal ion.

Front 30

What can flame emission spectroscopy be also used for?

Back 30

It can tell us the concentration of the metal ion. The lines become more intense at a higher concentration.

Front 31

What is an instrumental method?

Back 31

Instrumental methods are rapid.

Front 32

What are the positives of flame emission spectroscopy?(fes)

Back 32

.fes can analyse samples more rapidly than a flame test can.

. Because instrumental methods are sensitive, fes will even work on tiny a sample of metal compound.

. fes is more likely to identify a metal ion correctly than using a flame test.

Hint 32

Rapid, sensitive and accurate.

Front 33

How do you carry out the sodium hydroxide experiment?

Back 33

Firstly, you must have a test tube of magnesium, aluminium and Calcium ions. Then you must add sodium hydroxide to each of them. They should all Produce a white precipitate. However, it's is hard to distinguish between them. To solve this we add excess sodium hydroxide into the aluminium ion test tube which redissolves. We can distinguish the calcium ion by using the flame test.

Front 34

Complete the copper(II) reaction

Back 34

Copper(II) ions+ sodium hydroxide solution= a blue precipitate of copper(II) hydroxide

Front 35

Complete the iron(II) experiment

Back 35

Iron (II) ions+ sodium hydroxide solution= a green precipitate of iron (II) hydroxide

Front 36

Complete the iron (III) experiment

Back 36

Iron (III) ions+ sodium hydroxide solution= a brown precipitate of iron(III) hydroxide

Front 37

What is the test for a carbonate ion

Back 37

Firstly add dilute acid to the sample. The acid should react with the carbonate ion (we should see it fizzing) to produce carbon dioxide gas. However this still does not prove that we have carbon dioxide gas. We then must bubble the gas with limewater. If the limewater turns cloudy then carbon dioxide is present which means we started off with a carbonate ion.

Front 38

How do you test for halide ions

Back 38

Add nitric acid to the sample. Then add silver nitrate solution. Halide ions produce the precipitate of a silver halide. Each halide makes a different coloured precipitate.

Front 39

Name 3 halide ions.

Back 39

Chlorine, bromine and iodine

Front 40

What colour does a chloride ion make?

Back 40

Makes a white precipitate of silver chloride

Front 41

What colour does a bromide ion make?

Back 41

It makes a creamy precipitate of silver bromide

Front 42

What colour does a iodide ion make?

Back 42

It makes a yellow precipitate of silver iodide

Front 43

How do you test for sulfate ions?

Back 43

Add hydrochloric acid to our sample. Then add barium chloride. If it turns into a white precipitate then white ions are present