C12:ChemicalAnalysis

Question 1

what is a pure substance

Answer 1

a substance that is made up of just one substance, that substance can be either an element or a compound

Question 2

what is an impure substance

Answer 2

a mixture of two or more different elements or compounds

Question 3

what is used to identify pure elements and compounds

Answer 3

melting and boiling points

Question 4

what type of boiling points do pure substances have

Answer 4

specific boiling point

Question 5

what type of boiling points do

Answer 5

boil over a range of temperatures

Question 6

what are formulations

Answer 6

useful mixtures

Question 7

what are formulations designed for

Answer 7

to give a product the best possible properties to carry out its function

Question 8

how can scientists determine unknown substances in a solution

Answer 8

paper chromatography

Question 9

rf equation

Answer 9

substance/solvent

Question 10

hydrogen test

Answer 10

squeaky pop when you apply a lighted splint

Question 11

oxygen gas test

Answer 11

relights a glowing splint

Question 12

carbon dioxide test

Answer 12

turns limewater cloudy

Question 13

chlorine gas test

Answer 13

bleaches damp blue litmus paper white

Question 14

Li+ in flame lithium

Answer 14

crimson

Question 15

Na+ in flame sodium

Answer 15

yellow

Question 16

K+ in flame potassium

Answer 16

lilac

Question 17

Ca2+ in flame calcium

Answer 17

orange-red

Question 18

Cu2+ in flame copper

Answer 18

green

Question 19

what colour precipitate is formed with aluminium, calcium and magnesium ions form in a sodium hydroxide solution

Answer 19

white

Question 20

copper 2 ions with sodium hydroxide

Answer 20

blue precipitate

Question 21

iron 2 ions with sodium hydroxide

Answer 21

green precipitate

Question 22

iron 3 ions with sodium hydroxide

Answer 22

brown precipitate

Question 23

what do you do to test for a halide ion

Answer 23

add dilute nitric acid before the silver nitrate

Question 24

iodide ions with nitric acid and silver nitrate

Answer 24

yellow precipitate

Question 25

bromide ions with nitric acid and silver nitrate

Answer 25

cream precipitate

Question 26

chloride ions with nitric acid and silver nitrate

Answer 26

white precipitate

Question 27

how to identify carbonates

Answer 27

add limewater, it will turn cloudy

Question 28

how to identify sulfates

Answer 28

adding hydrochloric acid then barium chloride solution, this produces a white precipitate of barium sulfate

Question 29

what do modern instrumental techniques provide

Answer 29

fast, accurate and sensitive ways of analysing chemical substances

Question 30

example of an instrumental method

Answer 30

flame emission spectroscopy

Question 31

what does flame emission spectroscopy show us

Answer 31

which metal ions are present from their character line spectra, and also the concentration of a metal ions in a a solution