Chemical Analysis

Question 1

What does pure mean?

Answer 1

A substance that only contains one type of element or compound

Question 2

Pure substances do what over a range of temperatures?

Answer 2

Change state

Question 3

What is the name of the one temperature that pure substances melt and solidify at?

Answer 3

Melting point

Question 4

What is the name of the one temperature that pure substances boil and condense at?

Answer 4

Boiling point

Question 5

What is a formulation?

Answer 5

Mixtures that have been designed to have specific properties

Question 6

What happens during chromatography?

Answer 6

Mixtures separate into their components

Question 7

Why do the components separate during chromatography?

Answer 7

They move a different distance depending on its attraction for the paper and solvent

Question 8

What can chromatography be used for?

Answer 8

To identify artificial colours (in food) by comparing it with results from known substances

Question 9

Equation for Rf value

Answer 9

Distance moved by substance/distance moved by solvent

Question 10

What is the Rf value used for in chromatography?

Answer 10

To identify the component

Question 11

What are the properties of hydrogen?

Answer 11

Colourless, combines violently with oxygen when ignighted

Question 12

What is the test for hydrogen?

Answer 12

Lit splint and burns with squeaky pop

Question 13

What are the properties of chlorine?

Answer 13

A green, poisonous gas that bleaches dyes

Question 14

What is the test for chlorine?

Answer 14

Turns damp red litmus paper white

Question 15

What are the properties of oxygen?

Answer 15

A colourless gas that helps fuels burn more readily than in air

Question 16

What is the test for oxygen?

Answer 16

Relights a glowing splint

Question 17

What are the properties of carbon dioxide?

Answer 17

Colourless gas

Question 18

What is the test for carbon dioxide?

Answer 18

Turns limewater cloudy when bubbled through it

Question 19

What are instrumental methods?

Answer 19

Standard lab equipment is used to detect and identify substances

Question 20

What is flame emission spectroscopy used for?

Answer 20

To identify metal ions in a substance which contains more than 1 ion

Question 21

How does emission spectroscopy work?

Answer 21

The metal solution is placed in a flame and the light emitted is passed through a spectroscope

Question 22

What can the line spectrum produced by a substance in emission spectroscopy be used for?

Answer 22

Identifying ions, measuring the concentration of the metal ions

Question 23

What are flame tests used for?

Answer 23

To identify a metal ion in a substance that contains only 1 ion

Question 24

What colour does copper go in a flame test?

Answer 24

Green

Question 25

What colour does calcium go in a flame test?

Answer 25

Brick red

Question 26

What colour does lithium go in a flame test?

Answer 26

Crimson red

Question 27

What colour does potassium go in a flame test?

Answer 27

Lilac

Question 28

What colour does sodium go in a flame test?

Answer 28

Yellow

Question 29

What problem occur in flame test if a sample contains more than 1 metal ion?

Answer 29

It can be hard to detect them all as they can mask each other

Question 30

Carbonates react with dilute acids to form what?

Answer 30

Carbon dioxide + salt + water

Question 31

Most metal carbonates are insoluble, but which 2 aren't?

Answer 31

Potassium carbonate | Sodium carbonate

Question 32

What is a precipitate?

Answer 32

An insoluble solid that came out of a solution

Question 33

What substance do we add to a solution in metal ion precipitate tests?

Answer 33

Sodium hydroxide

Question 34

How do we name the precipitate formed in precipitate test?

Answer 34

Name of metal ion + hydroxide

Question 35

What colour is the precipitate of aluminium, Al3+?

Answer 35

White - dissolves if more sodium hydroxide is added

Question 36

What colour is the precipitate of calcium, Ca2+?

Answer 36

White

Question 37

What colour is the precipitate of magnesium, Mg2+?

Answer 37

White

Question 38

What colour is the precipitate of copper(II), Cu2+?

Answer 38

Blue

Question 39

What colour is the precipitate of iron(II), Fe2+?

Answer 39

Green

Question 40

What colour is the precipitate of iron(III), Fe3+?

Answer 40

Brown

Question 41

What is the positive result of a sulfate test?

Answer 41

A white precipitate of barium sulfate is formed

Question 42

How do we carry out the sulfate test?

Answer 42

By adding dilute hydrochloric acid and barium chloride to a solution

Question 43

What are the halide ions?

Answer 43

Chlroide, bromide and iodide (ions)

Question 44

What is the test for halides?

Answer 44

Adding silver nitrate in the presence of dilute nitric acid forms a silver halide precipitae

Question 45

A chloride gives a ...precipitate of silver chloride

Answer 45

White

Question 46

A bromide gives a ... precipitate of silver bromide

Answer 46

Cream

Question 47

An iodide gives a ... precipitate of silver iodide

Answer 47

Yellow

Question 48

Mobile phase of chromatography

Answer 48

Where molecules can move | Always liquid or gas

Question 49

Stationary phase in chromatography

Answer 49

Molecules can’t move | Can be solid or really thick liquid