papers

Question 1

how are the elements arranged in the periodic table

Answer 1

by increasing number of protons

Question 2

what observations are made when group 1 metals react with water

Answer 2

• moves on surface of water
• substance gets smaller/disappears

Question 3

how does a catalyst increase rate of reaction

Answer 3

• by providing an alternate pathway
• with lower activation energy

Question 4

why do we use a fume cupboard when working with chlorine

Answer 4

because chlorine is TOXIC/POIOSNOUS

Question 5

what does a double arrow in an equation mean

Answer 5

the reaction is reversible

Question 6

what state symbol goes with H20

Answer 6

liquid

Question 7

possible safety precautions

Answer 7

• goggles
• lab coat
• safety screen
• position class further away
• do in fume cupboard

Question 8

in the reaction between ammonia solution and sulfuric acid how does the sulfuric acid act in this reaction

Answer 8

as a proton donor

because it gives away its H (H+) which is essentially a proton

Question 9

explain why the chemical formula of ammonium sulfate is (NH4)2SO4

Answer 9

• because the charge of ammonium in +
• and the charge of a sulfate ion is 2+
• so two ammonium ions are used for one sulfate SO CHARGES BALANCE EACH OTHER

Question 10

what would the displayed formula of polypropene look like

Answer 10

Question 11

what type of reaction is it when a substance is HEATED on its own

Answer 11

decomposition

Question 12

why does it take several minutes for the ammonium chloride to form in the reaction between hydrochloric acid and ammonia solution

Answer 12

• gas particles move in random directions
• and collide with other particles in the air
• and collide with the sides of the test tube

which slows them down

Question 13

Explain the shape of the graph

Answer 13

• the reaction is exothermic so the temperature rises
• after 25cm3 the reaction is complete
• so no more heat is given out even as you add more sodium hydroxide

Question 14

describe a way of making solid calcium chloride conduct electricity

Answer 14

• by heating it
• until molten

Question 15

Explain what the chromatogram shows about the composition of the green food colouring

Answer 15

• contains three dyes
• contains dyes B and D
• because it has dots at the same level as B and D

Question 16

explain why diamond has a much higher melting point than C60 fullerene

Question 17

explain why lead metal forms at the negative electrode

Answer 17

• so the lead ions can gain electrons and form lead
• and because lead ions have a positive charge

Question 18

describe the industrial process used to separate crude oil into fractions

Answer 18

• crude oil is heated/vaporised
• then pumped into fractional distillation column
• fraction is cooler at the top than the bottom
• so the fractions condense at different heights depending on their boiling point

Question 19

give two features of a reaction in dynamic equilibrium

Answer 19

• rate of forwards reaction = rate of backwards reaction
• concentration of reactants and products remains constant

Question 20

describe a chemical test for a carboxylic acid

Answer 20

• add magnesium
• effervescence