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Chemistry > Electrochemistry * > Flashcards

Electrochemistry * Flashcards

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1
Q

What is electrochemistry?

A

the process by which ionic substances are broken down into simpler substances when an electric current is passed through them
or
using electrical energy to break ionic bonds

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2
Q

What is the electrolyte?

A

the ionic substance that is broken down

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3
Q

What may form at the electrodes during electrolysis?

A

metals and gases

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4
Q

What are cations?

A

positively charged ions (remember paw-sitive)

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5
Q

What are anions?

A

negatively charged ions

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6
Q

Where do the cations go during electrolisys?

A

to the cathode

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7
Q

Where do anions go during electrolysis?

A

to the anode

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8
Q

What charge does the cathode have?

A

negative

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9
Q

What charge does the anode have?

A

positive

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10
Q

Give the formula and charge of these cations:

silver
copper (II)
hydrogen
lead (II)
magnesium
aluminium
sodium

A

Ag+
Cu 2+
H+
Pb 2+
Mg 2+
Al 3+
Na+

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11
Q

Give the formulae and charge of these anions:

sulfate
nitrate
hydroxide
chloride
bromide
iodide

A

SO4 2-
NO3 -
OH-
Cl-
Br-
I-

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12
Q

Fill the gaps:

  • metal ions are all _______
  • non-metals are all ______
  • the only exception is ________ which is positive (______)
A
  • metal ions are all cations
  • non-metals are all anions
  • the only exception is hydrogen which is positive (cation)
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13
Q

Do cations gain or lose electrons at the cathode?

A

cations gain electrons

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14
Q

Do anions gain or lose electrons at the anode?

A

anions lose electrons

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15
Q

What is formed at the cathode? (aqueous electrolytes)

A

Whatever is lowest in the reactivity series

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16
Q

What is formed at the anode? (aqueous electrolytes)

A

oxygen and water unless something from group 7 is present (Cl-, Br-, I-)

17
Q

What is the half equation? (aqueous electrolytes)

A

4OH- –> 2H2O + O2 + 4e-

18
Q

What is electroplating?

A

when electrolysis is used to form a layer of metal over the surface of another metal

19
Q

Why is electroplating used?

A

to make objects made from a cheap material look more attractive (e.g. coat with silver or gold)
protect metals that corrode easily with a layer of a less reactive material

20
Q

What else is electrolysis used for? (2 points)

A
  • extraction of reactive materials
  • producing hydrogen from water
21
Q

What are electrochemical cells?

A

they consist of two half-cells connected together by an external circuit and a salt bridge

22
Q

(electrochemical cells)

What type of reactions occur in the half-cells and what kind of energy is produced?

A

exothermic reaction
electrical energy is produced instead of heat - this is the voltage/potential difference

23
Q

(electrochemical cells)

What happens when one of the reactants in the half cell is used up?

A

the reactions stop and a voltage is no longer produced

24
Q

What are fuel cells?

A

combustion reactions that produce electrical energy instead of heat

25
Q

What is an example of a fuel cell?

A

the hydrogen-oxygen fuel cell

26
Q

What happens at the anode in a hydrogen fuel cell?

A

hydrogen molecules break up into atoms which lose their electrons and form hydrogen ions

27
Q

What happens at the cathode in a hydrogen fuel cell?

A

the hydrogen ions gain electrons and then react with oxygen

28
Q

What is the overall reaction in a hydrogen fuel cell?

A

2H2 + O2 –> 2H2O

29
Q

What are 4 pros and cons of hydrogen fuel cells?

A

pros:
- unlimited supply of hydrogen (made from water)
- doesn’t produce greenhouse gases
- renewable resource
- very powerful

cons:
- hard to store
- requires a lot of energy to make
- expensive
- time-consuming

30
Q

What is a non-electrolyte?

A

doesn’t conduct electricity

31
Q

What happens during reduction?

A

an ion gains electrons and becomes an atom

32
Q

What happens during oxidation?

A

an atom loses electrons and becomes an ion

Chemistry (16 decks)

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