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AQA Chemistry > Chemical Changes > Flashcards

Chemical Changes Flashcards

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1
Q

how are metal oxides formed?

A

by reacting metals and oxygen

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2
Q

what is reduction and oxidation in terms of oxygen?

A
  • reduction: loss of oxygen
  • oxidation: gain of oxygen
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3
Q

what is the reactivity series?

A

a series arranged metals based on their reactivity which is based on their tendency to make positive ions

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4
Q

reactivity series

A

Please - potassium
Stop - sodium
Calling - calcium
Me - magnesium
A - aluminium
Careless - carbon
Zebra - zinc
Instead - iron
Try - tin
Learning - lead
How - hydrogen
Copper
Saves - silver
Gold

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5
Q

what is a displacement reaction?

A

when a more reactive element displaces another one from its compound

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6
Q

reactions of metals with water

A
  • potassium, sodium, lithium, calcium+ magnesium (highly reactive)=metal hydroxide and hydrogen gas=a lot of heat/explosive
  • more reactive the metal=more violent the reaction.
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7
Q

reactions of metals with acids

A
  • potassium, sodium and lithium react explosively with acids=a lot of heat energy is released in the reaction=hydrogen to explode.
  • magnesium, zinc and iron react less explosively=bubbles of hydrogen gas can be seen on the metal surface.
  • copper is extremely unreactive=below hydrogen in the reactivity series= x displace hydrogen from the acid
  • More reactive metals will react at a faster rate than less reactive metals
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8
Q

how are metals extracted?

A

Unreactive metals eg. gold= found in the Earth as metal
itself
- most metals are found as compounds (ores)
- metals less reactive than carbon extracted by reduction with carbon
- metals more reactive than carbon are extracted by electrolysis

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9
Q

what is OILRIG?
(electrons)

A

Oxidation
Is
Loss
Reduction
Is
Gain

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10
Q

what is neutralisation?

A

a reaction between an acid and an alkali/base

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11
Q

what is the difference between a bas and an alkali?

A

bases - insoluble metal hydroxides and metal oxides
alkalis - soluble metal hydroxides

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12
Q

neutralisation reaction

A

acid+base –> salt+water

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13
Q

required practical: soluble salts (copper crystals)

A
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14
Q

what is the pH scale?

A

a measure of the acidity or alkalinity of a solution, and can be measured using universal indicator or a pH probe

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15
Q

what are the ions of acids and alkalis?

A

acids - H+
alkalis - OH-

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16
Q

what is the neutral pH?

A

7

17
Q

what is the pH of an acid?

A

anything below 7

18
Q

what is the pH of an alkali?

A

anything above 7

19
Q

required practical: titrations

A
20
Q

what is a strong acid?

A

an acid that fully dissociates into its H+ ions eg. hydrochloric, nitric, sulfuric

21
Q

what is a weak acid?

A

an acid that partially dissociates into its H+ ions eg. ethanoic, citric, carbonic

22
Q

relationship between pH and H+ ion abundance

A

pH decreases by one, H+ ion concentration of the solution increases by a factor of 10

23
Q

what is the pH of an aqueous solution for a given concentration?

A

stronger acid=lower pH

24
Q

what is electrolysis?

A

electrolytes - liquids
and solutions are able to conduct electricity
- pass electric current through electrolytes causes the ions to
move to the electrodes
- positively charged ions move to the negative electrode (the cathode)
- negatively charged ions move
to the positive electrode (the anode)
- ions are discharged at the
electrodes producing elements

25
Q

what happens during electrolysis of molten ionic compounds?

A

the metal is produced
at the cathode and the non-metal is produced at the anode

26
Q

how are metals extracted with electrolysis?

A
  1. aluminium extracted from ore (bauxite) by electrolysis
  2. Bauxite has aluminium oxide in it= very high m.p= mixed with cryolite to down m.p
  3. molten mixture= free ions=conduct electricity
  4. positive Al+3 ions= cathode=pick up 3 3lectrons=Al atoms=sink to bottom of tank
  5. negative O-2 ions=anode=lose 2 electrons=oxygen atoms combine to form O2 molecules

half equations
Al+3 + 3e- –> Al
2O-2 –> O2 + 4e-

27
Q

electrolysis of aqueous solutions

A
  • because it’s aqueous H+ and OH- ions from water
  • at cathode=hydrogen is produced if the metal is more reactive than hydrogen
  • at anode= oxygen is produced unless solution contains halide ions
28
Q

required practical: electrolysis

A

AQA Chemistry (10 decks)

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