Chemistry Paper 1

Question 1

What is simple distillation used for ?

Answer 1

• to seperate solvent from solution

Question 2

What is fractional distillation used for ?

Answer 2

• to separate missile liquids

Question 3

What are 3 steps to make potable water ?

Answer 3

• sedimentation-> chemical added to sink small particles
• filtration-> sieve large objects
• chlorination-> chlorine added to kill microorganisms

Question 4

What is the plum pudding model ?

Answer 4

• sphere of positive charge with negative electrons dotted throughout

Question 5

What was John daltons theory ?

Answer 5

• atoms were solid of positive charge

Question 6

What was Ernest Rutherford atomic theory ?

Answer 6

• most of the atoms are empty space, positive nucleus, most mass in nucleus, later neutrons & protons discovered

Question 7

What is an isotope ?

Answer 7

• version of an element with different number of neutrons but same number of protons

Question 8

How was the past periodic table set out ?

Answer 8

• elements ordered by atomic mass, no gaps

Question 9

How did Mendeleev set out the periodic table ?

Answer 9

• elements ordered by atomic mass, left gaps fit undiscovered elements, grouped by chemical properties

Question 10

How is the modern periodic table set out ?

Answer 10

• elements ordered by atomic number, no gaps, grouped by number of electrons on outer shell, metals on left & non metals on right

Question 11

What is an ion ?

Answer 11

• an atom/ group of atoms with positive or negative charge

Question 12

What happens to metal ions when the firm an ion ?

Answer 12

• lose electrons-> form positively charged ions

Question 13

What happens to non metal atoms when they form an ion ?

Answer 13

• gain electrons-> form negatively charged ions

Question 14

What is an ionic lattice ?

Answer 14

• solid ionic compounds form a regular repeating 3D structure

Question 15

Why does ionic lattice have high melting point ?

Answer 15

• oppositely charged ions attract each other & held by strong electrostatic forces which require lots of energy to overcome

Question 16

What does it suggest if an ionic compound end in -ide ?

Answer 16

• it only contains 2 elements

Question 17

What does it suggest if an ionic compound end in -ate ?

Answer 17

• contains 3 or more elements, one of them is oxygen

Question 18

Why do simple covelant molecules have low melting points ?

Answer 18

• they have weak intermolecular forces which require little energy to overcome

Question 19

What are the properties of diamond ?

Answer 19

• each carbon atom joined to 4 other-> tetrahedral network, no free electrons, rigid & strong covelant bonds

Question 20

What are properties of graphite ?

Answer 20

• each carbon atom joined with 3 other-> hexagonal network, layers have weak forces-> can slide over each other, each carbon atom has 1 unbonded delocalised electron-> can conduct electricity

Question 21

What are the properties of graphene ?

Answer 21

• resembles single layer of graphite, high melting point, strong-> bc of large regular arrangement of carbon atoms joined by strong covelant bonds, conducts electricity-> delocalised electrons

Question 22

What are properties of fullerene ?

Answer 22

• resembles single layer of graphene, high tensile strength, conduct electricity bc delocalised electricity

Question 23

What are the properties of buckyballs?

Answer 23

• 60 atoms with weak forces, weak intermolecular forces-> need little energy to overcome-> slippery, lower melting points

Question 24

What is metallic lattice structure ?

Answer 24

• closely packed metal ions arranged In regular way with delocalised electrons & strong electrostatic force

Question 25

What is a closed system ?

Answer 25

• no substance can enter or leave • e.g. acid alkali neutralisation

Question 26

What is a non closed system ?

Answer 26

• substances can enter or leave • e.g. magnesium reacts with oxygen

Question 27

What colour does litmus paper turn in - acidic - neutral - alkaline

Answer 27

• acidic-> red • neutral-> purple • alkaline-> blue

Question 28

What colour does methyl orange turn in - acidic - neutral - alkaline

Answer 28

• acidic-> red • neutral-> yellow • alkaline-> yellow

Question 29

What colour does phenolphthalein turn in - acidic - neutral - alkaline

Answer 29

• acidic-> colourless • neutral-> colourless • alkaline-> pink

Question 30

What is general equation for neutralisation ?

Answer 30

• metal oxide + acid-> salt + water

Question 31

What happens in neutralisation reaction ?

Answer 31

• hydrogen ions from acid react with hydroxide ions from alkali which then forms water

Question 32

What is general equation for acid reacting with metal carbonate ?

Answer 32

• acid + metal carbonate-> salt + water + carbon dioxide

Question 33

What happens when acid reacts with metal carbonate ?

Answer 33

• hydrogen ions from acids react with carbonate ions to form water & carbon dioxide molecules

Question 34

What is the order of metal in reactivity series ?

Answer 34

• potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, copper, silver, gold

Question 35

What is oxidation ?

Answer 35

• gain of oxygen • loss of electrons

Question 36

What is reduction ?

Answer 36

• loss of oxygen • gain of electrons

Question 37

What is an ore ?

Answer 37

• rock that contains enough metal to make extracting economical

Question 38

What is carbon reduction method ?

Answer 38

• metal less reactive than carbon extracted from its compound by heat with carbon in a furnace

Question 39

What is phytoextraction ?

Answer 39

• plants grown on low grade ores-> absorb metal ions through roots-> burnt-> ashes contain higher metal ion concentration

Question 40

What is bleaching ?

Answer 40

• bacteria break down low grade ores to produce acidic solution (leachate) containing metal ions

Question 41

What is electrolysis ?

Answer 41

• process which breakdown ionic substances when direct current is passed through

Question 42

What happens in electrolysis ?

Answer 42

• cations attracted to cathode • anions attracted to anode • separates ions in electrolyte

Question 43

What happens at cathode & anode in case of molten ionic compound ?

Answer 43

• cathode-> reduction, metal ions reduced & solid metal deposits formed • anode-> oxidation, bubbles form

Question 44

What happened at cathode & anode in aqueous ionic compound ?

Answer 44

• cathode-> metal produced if less reactive than hydrogen, if not then hydrogen produced • anode-> oxygen produced from hydroxide ions unless a halide is present

Question 45

What is le chateliers principle ?

Answer 45

• if system at dynamic equilibrium is put under stress then position of equilibrium changes to reduce change & restore equilibrium

Question 46

What happens when position of equilibrium shifts left or right ?

Answer 46

• right-> rate of forward reaction increased & amount of product increased • left-> rate of backwards reaction increased & amount of reactant increases

Question 47

What happened when there is a change in pressure ?

Answer 47

• in gas reaction-> pressure increased-> equilibrium position moves in direction of less molecules-> bc making more of product with less gas molecules will decrease pressure-> restoring equilibrium

Question 48

What happened when there is a change in temperature ?

Answer 48

• in reversible reaction-> temperature increased-> equilibrium position moves in direction of endothermic process-> bc endothermic reactions absorb energy from increased temperature-> restoring equilibrium

Question 49

What happens when there is a change in concentration ?

Answer 49

• in solution reaction-> concentration of solute increased-> equilibrium shift in direction away from this solute