Chemistry 2

Question 1

Compare the polymerisation reaction used to produce poly(ethene) with the
polymerisation reaction used to produce a polyester.
[4 marks]

Answer 1

Poly ethene produced by addition polymerisation ,polyester by condensation polymerisation
Polyethene produced from one monomer whereas polyester is from two different monomers
Polyethene is only product formed, polyester and water is formed
Polyethene is repeating unit is a hydrocarbon whereas polyester is an water linkage

Question 2

Test for chlorine

Answer 2

Bleaches damp litmus paper white

Question 3

Oxygen

Answer 3

Put glowing splint inside a test tube containing oxygen it will relight the glowing splint

Question 4

Carbon dioxide

Answer 4

Adding co2 to like water makes the solution turn cloudy (sodium hydroxide)

Question 5

Hydrogen

Answer 5

Hold a lit splint at the end of a test tube containing hydrogen you’ll get a squeaky pop

Question 6

Carbonates

Answer 6

Add couple of drops of dilute acid to solution and connect a test tube to limewater of it turns cloudy carbonates are present

Question 7

Sulfate

Answer 7

Add few drops of barium chloride and hydrochloric acid to solution if present white precipitate of barium sulfate will form

Question 8

Halides

Answer 8

Add couple of drops of nitric acid and silver nitrate makes a silver halide chlorine give white precipitate bromide gives cream iodide gives yellow

Question 9

Flame test lithium

Answer 9

Crimson flame

Question 10

Sodium flame

Answer 10

Yellow

Question 11

Potassium flame

Answer 11

Lilac

Question 12

Calcium flame

Answer 12

Orange red flame

Question 13

Copper

Answer 13

Green flame

Question 14

Flame test practical

Answer 14

Clean platinum wire loop by dipping in dilute hcl and holding at blue flame til it burns with no colour dip in sample and put back in flame record colour

Question 15

Calcium precipitate

Answer 15

White

Question 16

Copper ppt

Answer 16

Blue

Question 17

Iron ppt fe2+

Answer 17

Green

Question 18

Iron fe3+

Answer 18

Brown

Question 19

Aluminium ppt

Answer 19

White at first but redissolves in excess NaOH to form a colourless solution

Question 20

Test for sulfates

Answer 20

Add barium chloride white ppt formed if sulfates present.

Question 21

Test for coloured precipitate

Answer 21

Add sodium hydroxide

Question 22

Calcium precipitate colour

Answer 22

White

Question 23

Test for ammonia gas

Answer 23

Turns damp red litmus paper blue as its alkaline

Question 24

Test for ammonium ions

Answer 24

Add sodium hydroxide to substance and gently heat if ammonia is given off its present

Question 25

Test for hydroxide ions

Answer 25

Turns red litmus paper blue

Question 26

Average bond enthalpy

Answer 26

Energy needed to break one mole of bonds in gas phase averaged over many different compounds

Question 27

The stronger the attraction

Answer 27

The higher the bond enthalpy and the shorter the bond length