chemistry paper 1 electrolysis

Question 1

define electrolysis and an electrolyte

Answer 1

electrical energy from a direct current supply, decomposes electrolytes.

an ionic compound that’s molten or dissolved in water

Question 2

electrode…

Answer 2

a rod made of a metal or
graphite which carries the current
into or out of the electrolyte

Question 3

cations are positive ions and are attracted to…
anions are negative ions and are attracted to..

Answer 3

the negative cathode
the positive anode

Question 4

reduction takes place at the..
oxidation takes place at the…

Answer 4

negative cathode
positive anode

Question 5

electrolysis of dissolved salts is carried out using …
metal produced at..
non-metal produced at…
when molten salt is electrolysed

Answer 5

electrolysis
cathode
anode
ions r discharged as atoms or molecules at the electrodes

Question 6

what products r formed at the anode and cathode during the electrolysis of copper chloride?

Answer 6

cathode - Cu2+ and H+ ions. Cu ions discharged mre readily. Brown solid

anode - Cl- and OH- ions. Cl ions dishcarged mre readily, cl forms as Pale green gas

Cop Cl decomposes but h20 no change

Question 7

what porducts r formed at the anode and cathode during the electrolysis of sodium chloride

Answer 7

cathode - Na+ and H+ ions. H+ discharged more readily than sodium. Hydrogen gas formed

anode - Cl- and OH- ions , Cl ions discharge more readily than hydroxide. CL forms pale green gas

sodium chloride decomposes to form hydrogen and clhorine. Na and OH- ions remain in solution

Question 8

what porducts r formed at the anode and cathode during the electrolysis of sodium sulfate

Answer 8

cathode - Na+ and H+ ions. H+ ions discharged more readily. Hydrogen gas forms.

anode - sulfate ions & OH- . OH- ions discharged more readily
than sulfate
ions, so oxygen gas is formed.

overall, water decomposes to form hydrogen and oxygen

Question 9

what porducts r formed at the anode and cathode during the water being acidified w sulfuric acid.

Answer 9

Cathode: H+ ions are attracted. Hydrogen ions discharged forming hydrogen gas

Anode: SO4 2- and OH- ions attracted. Hydroxide ioms discharged more readily. Oxygen gas formed

overall: water decomposes to form
hydrogen and oxygen:
2H2O(l) → 2H2(g) + O2(g

Question 10

How can electrodes be used to purify copper using copper electrodes?

Answer 10

-copper atoms in in anode loose electrons to become copper ions
-these dissolve in the solution and migrate to cathode where they r deposited as pure copper

Question 11

list the reactivity series

Answer 11

potas , sod, calc, mag, alum, Zn, Iron, copp silver gold

Question 12

which metals from the RS react with cold water to form hydrogen and a metal hydroxide?

Answer 12

potass, sodium ,calc

Question 13

which metals from the RS react slowly w cold water but react w steam to form hydrogen and a metal hydroxide

Answer 13

mag, allum, Zn , iron

Question 14

which elements dont react w hot or cold water or dilute acid from RS?

Answer 14

copper silver and gold

Question 15

which elements from the RS react violently with dilute acid?

Answer 15

potass and sodium

Question 16

which elements from the RS react w dilute acid to form hydrogen and a salt solution?

Answer 16

calc, mag , allum, Zn , iron

Question 17

the higher up the metal in the RS…

Answer 17

the easily it looses electrons

Question 18

what is extraction?
whats an ore?

Answer 18

a process where a metal is obtained from its ore
an ore is a rock that contains enough of a compound to extract a metal

Question 19

what method of extraction is used for potasssium to alumnium in the reactivity series?

Answer 19

electrolysis of a molten compound

Question 20

what method extraction can be used for zinc to copper in the RS

Answer 20

heat an ore with carbon

Question 21

what method of extraction can be used for silver and gold

Answer 21

non as its an uncombined element

Question 22

define bioleaching (a form of metal extraction)

define phytoextraction

Answer 22

using bacteria to extract metal from their ores

using plants to extract metal from their ores. Plants are burnt to form ash from which the metal is extracted

Question 23

adv and disadv of both bioleaching and phytoextraction

Answer 23

adv - no harmful gases produced, causes less damage to landscape than mining

very slow

Question 24

adv and disadv of just bioleaching

Answer 24

doesnt require high temps
toxic substances produced, damage to environ

Question 25

adv and disadv of just phytoextraction

Answer 25

can extract metals from contaminated soils
more expensive than mining some ores, growing plants depend on weather conditions

Question 26

what is oxidation and reduction in terms of oxygen?

Answer 26

oxidation is the gain of oxygen and reduction as the
loss of oxygen

Question 27

how do you obtain a metal from metal oxide cores?

Answer 27

oxygen is removed . Once removed the compound is said to be reduced

Question 28

define corrosion and rusting

Answer 28

when a metal reacts with oxygen (becomes oxidised) making the metal weaker over time.

rusting - the corrosion of iron or steel. H20 or 02 must be present

Question 29

why doesnt metals like aluminium rust?

Answer 29

their surfaces form a protective oxide layer which prevents further reaction

Question 30

what are advantages of recycling metals?
disadv

Answer 30

-natural reserves of metal ores will last longer
-less waste metals end up in landfill sites

-costs and energy using in collecting transporting and sorting metals

Question 31

what is a life cycle assessment and what are the 4 stages?

Answer 31

-its carried out to work out the environmental impact of a product and whether its worthwhile to manufacture and recycle the product
1. using the product
2. disposal of product
3. obtaining and processing raw materials
4. manufaturing and packaging the product

Question 32

most metals = transition metals and their typical properties are….

Answer 32

a high melting point
b high density
c the formation of coloured compounds
d catalytic activity of the metals and their compounds
as exemplified by iron

Question 33

what are reversible reactions? ⇌
dynamic equilibrium?

Answer 33

a reaction that works in both direction

when the forwards and backwards reactions in a reversible chem reaction are occuring at the same rate

Question 34

what conditions are needed for the haber process?

Answer 34

a temperature 450 °C
b pressure 200 atmospheres
c iron catalyst

Question 35

what is sacrificial protection

Answer 35

using a more reactive metal to prevent iron from rusting

Question 36

how is the position of a dynamic equilibrium
affected

Answer 36

a temperature
b pressure
c concentration

Question 37

describe the formation of ammonia

Answer 37

• reversible reaction
  between nitrogen (extracted from the air) and hydrogen
  (obtained from natural gas)
  -it can reach a dynamic equilibrium

Question 38

what is electroplating? whys it used

Answer 38

using electricity to coat one metal with a thin layer of another metal
to improve its appearance; to improve its
resistance to corrosion/rusting

Question 39

define galvanising

Answer 39

coating iron or steel with a thin layer of zinc to improve its resistance to rusting
zinc improves corrosion resistance by stopping water reachin iron or steel (acting as a sacrificial metal)

Question 40

Explain why converting pure metals into alloys
often increases the strength of the product

Answer 40

making it into an alloy adds extra atoms which distorts the regular structure so the atoms can no longer slide over each other as easily making it less malleable

Question 41

what is an alloy
alloy steels are made by..

Answer 41

a mixture of metals
deliberately adding other elements to iron

Question 42

stainless steels…

Answer 42

resist rusting. it contains chromium that reacts with o2 in the air, creating a layer of chromium oxide thick enough to stop air and water reaching metal below

Question 43

how are aluminium copper and gold used