Electrolysis Flashcards Preview

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Flashcards in Electrolysis Deck (36):
1

We can only do electrolysis on

Ionic compounds

2

Sulphate charge

SO4 2-

3

Nitrate charge

NO3 -

4

Phosphate charge

PO4 3-

5

Carbonate charge

CO3 2-

6

Hydroxide charge

OH -

7

What happens in electrolysis

Electrical energy is transferred to decompose the electrolyte

8

What is the Electrolyte

The liquid we are electrolysing

9

What is the ionic compound broken down into

Positive cations and negative anions

10

What should the electrolyte be and why

A liquid (molten or dissolved) so that the ions are free to move and carry a current

11

What current must the electrodes be connected with and why

DC current because the current needs to flow one way so that no electrons are lost

12

Electrodes and how they work

Negative cathode which attracts positive cations (metals and hydrogen) and a positive anode which attracts negative anions (non-metals and hydroxides) (opposite charges attract)

13

Electrolysis def

The breaking down (decomposition) of an ionic compound using electric energy from a direct current

14

Electrode def

A conductor through which electricity enters or leaves a substance

15

Electrolyte def

An ionic compound (liquid) with free moving ions

16

Electrolysis of copper sulphate solution

Cu2+ SO4 2- (CuSO4)
The cations copper or hydrogen will travel to the cathode as electrons will leave the cathode. The sulphate or hydroxide anions will travel to the anode. It depends on which ions are less reactive; they will be discharged.
Copper will be made as it is less reactive than hydrogen. The hydrogen ions are donated electrons and become hydrogen molecules.
Oxygen will be made.

17

Test for sulphur

It's a yellow gas

18

Electrolysis of solutions

The less reactive ions will be discharged. A the anode the "simplest" ion is discharged. At the cathode, the metal is discharged if it is less reactive than hydrogen. If it is more reactive, then the hydrogen is discharged.

19

Inert

Not involved in electrolysis as they don't react e.g. graphite electrodes (the conduct electricity well)

20

Anything above carbon uses ____ under uses ____ and silver gold and platinum are extracted from ___

Electrolysis, reduction by being heated with carbon, mining

21

Ores def

Rocks that contain a metal which we can extract

22

Malachite

Copper

23

Bauxite

Aluminium

24

Cinnabar

Mercury

25

Galena

Lead

26

Haematite

Iron

27

Reduction is the loss of ____ and gain of ____

Oxygen and electrons (to the cathode)

28

Oxidation is the gain of ____ and loss of ____

Oxygen and electrons (from the anode)

29

Reducing agent

Causes other things to reduce/steal their oxygen

30

Spectator ion

Ions that have been left out as they don't change

31

Why recycle

Resources are finite and limited, sustainable, energetically favourable, cheaper, avoids landfills which are bad for the environment, less CO2, use less fossil fuels

32

Life cycle

Obtaining and processing raw materials, manufacturing and packaging product, using product, disposal of product

33

Formation of copper chloride solution products

CuCl2
Cu2+ + 2e- --> Cu at the cathode (reduction)
2Cl- --> Cl2 + 2e- at the anode (oxidation)

34

Formation of water acidified with sulphuric acid products

H2O + H2SO4
2H+ + O2- + 2H+ + SO42-
...

35

REDOX reaction of magnesium and copper sulfate

Copper + magnesium sulfate (displacement)
(Cu + MgSO4)
(Reduction) (Oxidation)

36

Formation of molten lead bromide products

PbBr2 is a pure substance with only lead and bromide ions. It is the electrolyte. The electrodes are put into the electrolyte and a direct current (battery or cell) applies the electricity. The positive lead ions migrate/transit to the negative cathode and the negative bromide ions migrate/transit to the positive anode.
Cathode: Pb2+ + 2e- --> Pb
Anode: 2Br- --> Br2 + 2e-