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Flashcards in Electrolysis Deck (22):
1

What is an electric current

A flow of electrons or ions

2

Why do covalent compounds not conduct electricity

They don't have charged particles so they consist of atoms or molecules therefore they can't conduct electricity, even if they melt or dissolve in water.

3

Why do ionic compounds conduct electricity only when molten or in solution

Ionic compounds have charged particles but can only conduct if it is molten or dissolved in water because only in the liquid or aqueous state can the ions move to the oppositely charged electrode.

4

Sodium chloride electrolysis

Diaphragm cell
Hydrogen gas at cathode
Chlorine gas at anode
Sodium hydroxide in solution

2H + + e- ——> H2
2Cl- ——> Cl2 + e-

Uses:
- chlorine sterilises water
- hydrogen for Haber process and to change oils and fat into margarine
- sodium hydroxide chemical industry for soap and bleach

5

Copper sulfate electrolysis

Copper : cathode (Cu2+ + 2e- ——> Cu)
Hydroxide : anode (

6

Electrolyte definition

Liquid that conducts electricity

7

Electrolysis definition

Separation of an ionic compound using electricity

8

Cation/cathode

Positively charged ion/ negatively charged electrode

9

Anion/ anode

Negatively charged ion/ positively charged electrode

10

Electrode definition

Terminals of battery dipping into an electrolyte

11

Inert definition

Unreactive atom

12

Definition of reduction and oxidation

Reduction : gaining electrons, occurs at the cathode

Oxidation : losing electrons, occurs at the anode

13

Lead bromide products

Lead, bromine

14

What does electrolysis involve

It involves the formation of new substances when ionic compounds conduct electricity

15

Sulfuric acid products

4 hydrogens, 1 oxygen

16

Sodium chloride products (L)

2 sodiums, 1 chlorine

17

Sodium chloride products (aq) diaphragm cell

Hydrogen, chlorine

- titanium anode
- mild steel cathode

18

Copper sulfate (aq)

2 coppers, 1 oxygen

19

Rules of electrolysis: cathode

Metal, except with reactive metals (K Na Li Mg) in which case H2 gas is produced plus a solution of metal hydroxide

20

Rules of electrolysis: anode

Non metal, except sulphates in which case O2

21

Electroplating

You put what you want to electroplate at the cathode (as metals go to the cathode) and a layer of metal is electrolysed onto your item. Corrosion resistant and pretty

22

Purify copper

A large lump of impure copper is used at the anode and the cathode is made of pure copper. That's the anode, instead of anions losing electrons, neutral copper atoms lose electrons to become copper ions ( cu -> cu2+ +2e- ) , they then move through the electrolyte to the cathode where they become copper atoms again ( cu2+ +2e- -> cu ) The anode loses mass as copper atoms leave it and the cathode gains mass as copper atoms join it. The impurities sink to the bottom as a pile of sludge.