chemistry topic 8

Question 1

what is a pure substance

Answer 1

a single element or compound

Question 2

what is a formulation

Answer 2

mixture designed as a useful product - made by mixing the
components in carefully measured quantities

Question 3

what are some examples of formulations

Answer 3

paints
medicines
fertilisers

Question 4

what does chromatography do

Answer 4

separates soluble mixtures from a solvent

Question 5

what is the formula for Rf

Answer 5

Rf = distance moved by substance (dye) / distance moved by solvent

Question 6

what does the Rf value of a dye depends on

Answer 6

The solubility of the dye in the solvent

The attraction of the dye to the paper.

Question 7

If a dye travels further up the paper:

Answer 7

It is more soluble in the solvent

has less attraction to the paper.

Question 8

how to test for oxygen

Answer 8

test: glowing splint
result: re-lights

Question 9

how to test for hydrogen

Answer 9

test: burning splint
result: squeaky pop

Question 10

how to test for carbon dioxide

Answer 10

test: bubble through limewater

result: limewater goes cloudy

Question 11

how to test for chlorine

Answer 11

test: damp litmus paper

result: Bleached – blue to white

Question 12

how to test for lithium ions

Answer 12

flame test: crimson flame

Question 13

how to test for sodium ions

Answer 13

flame test: yellow flame

Question 14

how to test for potassium ions

Answer 14

flame test: lilac flame

Question 15

how to test for copper ions

Answer 15

flame test: Green flame

add sodium hydroxide: blue precipitate

Question 16

how to test for calcium ions

Answer 16

flame test: orange-red flame

add sodium hydroxide: white precipitate (does not dissolve when more added)

Question 17

how to test for magnesium ions

Answer 17

add sodium hydroxide: white precipitate (does not dissolve when more added)

Question 18

how to test for aluminium ions

Answer 18

add sodium hydroxide: white precipitate (does dissolve when more added)

Question 19

how to test for iron (ii) ions

Answer 19

add sodium hydroxide: green precipitate

Question 20

how to test for iron (iii) ions

Answer 20

add sodium hydroxide: brown precipitate

Question 21

how to test for sulfate ions

Answer 21

add barium chloride with hydrochloric acid: white precipitate

Question 21

how to test for carbonate ions

Answer 21

add dilute acid: bubbles of gas that turn limewater cloudy

Question 21

how to test for chloride ions

Answer 21

add silver nitrate with nitric acid:
white precipitate

Question 21

how to test for iodine ions

Answer 21

add silver nitrate and nitric acid: yellow precipitate

Question 21

how to test for bromide ions

Answer 21

add silver nitrate with nitric acid: cream precipitate

Question 21

what are the benefits of Elements and compounds being detected and identified using Instrumental methods

Answer 21

Accurate Sensitive Rapid

Question 21

what is Flame emission spectroscopy used for

Answer 21

its used to identify and measure concentrations of metal ions in solution.

Question 21

how is Flame emission spectroscopy done

Answer 21

Put sample into flame. Light given out is passed through a spectroscope. Each metal has their own patterns of bands which allows them to be identified as being present in the solution.