purity, formulations and chromatography

Question 1

what are formulations?

Answer 1

mixtures of different ingredients that creates a useful product that contains advantageous characteristics (eg, acetone (nail polish remover))

Question 2

what is a pure substance?

Answer 2

a single element or compound not mixed

Question 3

describe what chromatography is for?

Answer 3

a laboratory technique for separating mixtures

Question 4

what can happen if the chromatography paper touches the sides of the glass beaker?

Answer 4

capillary action, will spread out unevenly

Question 5

what is the equation for the Rf value?

Answer 5

distance moved by substance/distance moved by solvent

Question 6

what’s the stationary phase?

Answer 6

the chromatography paper (doesn’t move)

Question 7

what is the mobile phase?

Answer 7

the solvent (moves)

Question 8

why isn’t water always the only solvent used in this practice?

Answer 8

because not all substances dissolve in water so other solvents are used

Question 9

why may a lid be used?

Answer 9

because different solvents evaporate at different temperatures and they could evaporate while the chromatogram is developing as they may be more volition

Question 10

what is the test for oxygen?

Answer 10

manganese oxide+ hydrogen peroxide

light a splint and blow it out then put it into the test tube

it will re-light if oxygen is present

Question 11

what is the test for hydrogen?

Answer 11

magnesium+hydrochloric acid
put a bung on top of test tube and when ready put a lit splint into the tube
it will make a squeaky pop noise and put out the fire

Question 12

what is the test for carbon dioxide?

Answer 12

sodium carbonate+hydrochloric acid in one test tube and lime water in another
quickly using a pipette transfer the co2 produces into the limewater
it should go cloudy

Question 13

what is the test for chlorine?

Answer 13

damp litmus paper will bleach white

Question 14

what colour does lithium go in the flame test?

Answer 14

crimson/ruby red

Question 15

what colour does sodium go in the flame test?

Answer 15

yellow

Question 16

what colour does potassium go in the flame test?

Answer 16

lilac

Question 17

what colour does calcium go in the flame test?

Answer 17

red/orange

Question 18

what colour does copper go in the flame test?

Answer 18

green

Question 19

describe the flame test?

Answer 19

pour about 1cm depth of chloride solutions into test tubes and dip a wet splint into each of the solutions and then put in the roaring blue flame and observe

Question 20

describe the carbonate test

Answer 20

• 1cm depth of all the sodium solutions and then limewater in the last one
• add hydrochloric acid to each one at a time and using a pipette transfer gases produced to the lime water

Question 21

describe the sulphate test

Answer 21

• 1cm depth of each sodium solutions into all five test tubes
• then add HCL and barium chloride (1cm depth)
• record results

Question 22

describe the halide test

Answer 22

• 1cm depth of each sodium solutions into all five test tubes
• add a few drops of nitric acid and silver nitrate solution
• record results

Question 23

how do you identify Ions?

Answer 23

add sodium hydroxide to the different metals and it will create a precipitate

Question 24

what precipitate does magnesium produce in the identifying ions test?

Answer 24

white

Question 25

what precipitate does calcium produce in the identifying ions test?

Answer 25

white

Question 26

what precipitate does aluminium produce in the identifying ions test?

Answer 26

white but disappears when NaOH is in excess

Question 27

what precipitate does copper II produce in the identifying ions test?

Answer 27

blue

Question 28

what precipitate does iron II produce in the identifying ions test?

Answer 28

green

Question 29

what precipitate does iron III produce in the identifying ions test?

Answer 29

brown/dirty brown

Question 30

why would you use an instrumental method instead?

Answer 30

more accurate, sensitive and rapid

Question 31

name an instrumental test

Answer 31

flame emission spectroscopy

created a spectrum of light produced by flames which can be compared