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Flashcards in C6 Deck (22)
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1
Q

what is electrolysis

A

using an electric current to break down an ionic compound

2
Q

what is an ionic compound called in an electrolysis reaction

A

the electrolyte

3
Q

what is the positive and negative electrodes called

A
positive = anode
negative = cathode
4
Q

what are electrodes made of and why

A

an unreactive substance e.g. graphite or platinum metal so that the electrodes don’t react with the electrolyte or the products made in electrolysis

5
Q

where do the positively charged ions and the negatively charged ions move towards

A

positive - cathode

negative- anode

6
Q

what happens to the ions at the electrodes

A

they lose their charge and become elements sometimes giving off gases or depositing metals in the process

7
Q

what do covalent compounds have to do before being electrolysed

A

react or ionise in water to form ions

8
Q

what does OILRIG help us understand about electrons

A

oxidation is loss

reduction is gain

9
Q

at the cathode reduction of a positive ion would take place. what is an expanse of a half equation of this (reduction of lead)

A

2+ -

Pb + 2e = Pb

10
Q

at the anode oxidation of a negative ion would take place. what is an example of a half equation of this (oxidation of bromine)

A

_ _

2Br = Br2 + 2e

11
Q

what happens if 2 elements can be produced at an electrode

A

the less reactive will usually be formed

12
Q

what ore do you get aluminium oxide from

A

bauxite

13
Q

why do you mix aluminium oxide with molten cryolite before electrolysis

A

because aluminium oxide has a melting point of 2050c so mixing it with molten cryolite allows it to be electrolysed at 850c

14
Q

what products do you get at the anode

A

oxygen given off from discharged hydroxide ions

a halogen produced if the electrolyte is a solution of a halide

15
Q

why do carbon anodes have to be replaced regularly

A

because they gradually burn away as the oxygen reacts with the hot carbon anodes forming carbon dioxide gas

16
Q

what is brine

A

concentrated NaCl solution

17
Q

what 3 useful products do you get when electrolysing brine

A

chlorine gas (anode)

hydrogen gas (cathode)

sodium hydroxide solution

18
Q

what salts do sulphuric, hydrochloric and nitric acid form

A

sulfide, chloride and nitrate

19
Q

acid + alkali = ?

A

salt + water

20
Q

acid + base = ?

A

salt + water

21
Q

acid + metal = ?

A

salt + hydrogen

22
Q

acid + carbonate = ?

A

salt + carbon dioxide + water