Electrochemistry 🧪 Flashcards

1
Q

When an electric current is passed through a molten ionic compound or aqueous solution of ionic compounds

A

The compound decomposes or breaks down

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2
Q

Covalent compounds can’t conduct electricity because

A

They do not undergo electrolysis

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3
Q

Ionic compounds in the solid state cannot conduct electricity either since

A

They have no free ions that can move and carry the charge

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4
Q

Electrode

A

A rod of metal or graphite which an electric current flows into or out of an electrolyte

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5
Q

Electrolyte

A

Is the ionic compound in a molten or dissolved solution that conducts the electricity

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6
Q

Anode

A

The positive electrode of an electrolysis cell

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7
Q

Anion

A

A negatively charged ion which is attracted to the anode

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8
Q

Cathode

A

The negative electrode of an electrolysis cell

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9
Q

Cation

A

A positively charged ion which is attracted to the cathode

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10
Q

Metals and hydrogen form positively charged ions so

A

Either a metal or hydrogen gas is formed at the cathode

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11
Q

Non-metals form negatively charged ions and so

A

non-metals (except hydrogen) are formed at the anode

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12
Q

PANIC

A

Positive Anode Negative Is Cathode

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13
Q

During electrolysis,

A

current needs to flow around the circuit

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14
Q

In order for current to flow around the circuit

A

Charge must be transferred around the circuit by charge carriers

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15
Q

The power supply provides the cathode with

A

A supply of electrons, causing it to become negatively charged

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16
Q

Positive ions (Cathodes) in the electrolyte move

A

Towards the cathode where they gain electrons

17
Q

Negative ions (anions) move towards

A

The anode where they lose electrons

18
Q

The electrons move from the

A

Anode back towards the power supply

19
Q

Electrons are

A

The charge carriers in the external circuit

20
Q

Ions are

A

The charge carriers in the electrolyte

21
Q

A binary ionic compound

A

Is one consisting of just 2 elements joined together by ionic bonding. When these compounds undergo electrolysis they always produce their corresponding elements

22
Q

The cathode product

A

Will always be the metal

23
Q

The product formed at the anode

A

Will always be the non-metal

24
Q

Brine can be electrolysed, when it is it

A

Produces bubbles of gas at both electrodes as chlorine and hydrogen are produced leaving behind sodium hydroxide solution

25
Q

Dilute sulfuric acid can be electrolysed, when it is

A

Bubbles of gas are seen at both electrodes. At the negative electrode H+ ions are attracted to the cathode and form hydrogen gas. OH- ions are attracted to the anode and form Oxygen gas and Water

26
Q

Determining what gas is produced
Oxygen
Chlorine
Hydrogen

A

Oxygen: glowing splint relights
Chlorine: blue litmus paper turns red then white
Hydrogen: squeaky pop sound

27
Q

Aqueous solutions will always have

A

Water present

28
Q

In the electrolysis of aqueous solutions

A

Water molecules dissociate producing H+ and OH- ions these ions are also involved in the process and their chemistry must be considered

29
Q

Now there is an electrolyte containing

A

ions from the compound plus ions from the water

30
Q

Which ions gat discharged and at which electrode depends on

A

The relative reactivity of the. Ions involved

31
Q

Concentrated and dilute solutions of the same compound give

A

Different products, for anions the more concentrated ion will tend to be discharged over a more dilute ion

32
Q

Negatively charged OH- ions and non metal ions are attracted to

A

The positive electrode

33
Q

If halide ions (Cl-, Br-,I-) and OH- are present then

A

The halide ion is discharged at the anode, loses electrons and forms a halogen

34
Q

If no halide ions are present

A

Then OH- is discharged at the anode, loses electrons and forms Oxygen gas

35
Q

The concentration of the solution also affects which ion is discharges

A

Concentrated halide solution: the halogen forms at the anode
Dilute halide solution: oxygen is formed at the anode

36
Q

Positively charged H+ and metals ions are attracted

A

to the negative electrode but only one will gain electrons. Either hydrogen gas or metal will be produced

37
Q

If the metal is above hydrogen in the reactivity series

A

Then hydrogen will be produced and bubbling will be seen at the cathode this is because the ions of the more reactive metal will remain in the solution causing the ions of the least reactive metal to be discharged

38
Q

At the cathode hydrogen will be produced unless,

A

The positive ions from the ionic compound are less reactive than hydrogen, in which case the metal is produced

39
Q

Reactivity series

A

Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminum
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold