Chemistry 5 Electricity And Chemistry

Front 1

Define electrolysis

Back 1

The chemical effectof electricity on ionic compounds, causingthem to break up into simpler substances,usually elements.

Front 2

What is an electrode?

Back 2

A conductor through which electricity enters or leaves an object, substance, or region.

Front 3

What is an electrolyte?

Back 3

The mixture being electrolysed in electrolysis and must be liquid to allow for the ions to move.

Front 4

What is the Anode?

Back 4

Positive electrode

Front 5

What is the cathode?

Back 5

Negative electrode

Front 6

Describe electrolysis in terms of the ionspresent and the reactions at the electrodes.

Back 6

-When compounds have been broken down, the positive ions (Cations) move to the cathode where they gain electrons usually forming a metal (or hydrogen)

-Negative ions (anions) move to the anode (the positive electrode) where they lose electrons usually forming a non-metal (not hydrogen).

Front 7

What happens at the anode during the electrolysis of molten lead(II) bromide?

Back 7

-bromide ions (Br-) are attracted to the positive electrode

-the bromide ions are forced to give away their extra electron to form bromine atoms

-the bromine atoms join up in pairs to form diatomic bromine molecules (Br2).

-the ion-electron half equation for this reaction is:2Br-(l) → Br2(g) + 2e-

Front 8

What happens at the cathode during the electrolysis of molten lead (II) bromide?

Back 8

-lead(II) ions (Pb2+) are attracted to the negative electrode

-the Pb2+ ions are forced to accept two electrons -the ion-electron half equation for this reaction is:Pb2+(l) + 2e- → Pb(l)

Front 9

What are the products of the electrolysis of molten lead (II) bromide?

Back 9

LEAD METAL AT THE CATHODE-

The lead will form as a liquid at the bottom of the reaction vessel.

BROMINE AT THE ANODE-

The bromine appears as a brown gas at the positive electrode.

Front 10

What happens at the anode during the electrolysis of aqueous copper chloride?

Back 10

-colourless chloride ions (Cl-) are attracted to the positive electrode

-the chloride ions are forced to give away their extra electron to form chlorine atoms

-the chlorine atoms join up in pairs to form diatomic chlorine molecules (Cl2)

-The ion-electron half equation for this reaction is:2Cl-(aq) → Cl2(g) + 2e-

Front 11

What happens at the Cathode during the electrolysis of aqueous copper chloride?

Back 11

-copper(II) ions (Cu2+) are attracted to the negative electrode

-the blue Cu2+ ions are forced to accept two electrons

-the ion-electron half equation for this reaction is:Cu2+(aq) + 2e- → Cu(s)

Front 12

What are the products of the electrolysis of aqueous copper chloride?

Back 12

Copper metal at the negative electrode

The copper forms as a brown solid on the negative electrode.

Chlorine gas (Cl2) at the positive electrode

The chlorine appears as a gas with a characteristic smell at the positive electrode.

Front 13

What happens at the cathode during the electrolysis of dilute sulphuric acid?

Back 13

The gas produced at the cathode burns with a 'pop' when a sample is lit with a lighted splint. This shows that the gas is hydrogen.

Front 14

What happens at the anode during the electrolysis of dilute sulphuric acid?

Back 14

The gas produced at the anode relights a glowing splint dipped into a sample of the gas. This shows that the gas is oxygen.

Front 15

What is generally made at the anode?

Back 15

Non metals other than hydrogen.

Front 16

What is generally made at the cathode?

Back 16

Metals and hydrogen.

Front 17

What happens at the anode and cathode during electrolysis of copper sulphate?

Back 17

-the cathode gets coated with copper

-bubbles of oxygen are given off at the anode

Front 18

Describe the electroplating of metals, usinglaboratory apparatus.

Back 18

The negative electrode should be the object that is to be electroplated

The positive electrode should be the metal that you want to coat the object with

The electrolyte should be a solution of the coating metal, such as its metal nitrate or sulfate

Front 19

Describe, in outline, the chemistry of the manufacture of aluminium from pure aluminium oxide in molten cryolite.

Back 19

-It is dissolved in molten cryolite.

-Aluminium metal forms at the negative electrode and sinks to the bottom of the tank\

-Oxygen forms at the positive electrodes. This oxygen reacts with the carbon of the positive electrodes, forming carbon dioxide, and they gradually burn away.