Electrolysis

Question 1

What is Electrolysis?

Answer 1

Breaking down ionic compounds using electricity

Question 2

Why must the ionic compound be molten or dissolved?

Answer 2

Ions must be able to move. Solid Ions are in a fixed position and therefore cannot generate a current

Question 3

What is an Electrolyte?

Answer 3

A liquid or solution that undergoes electrolysis

Question 4

what colour coating appears on the cathode when Lead Bromide is undergoing electrolysis?

Answer 4

Silver Coating

Question 5

How can we check if the circuit is working or the liquid/solution is an electrolyte?

Answer 5

Place a bulb in the circuit and wait for it to turn on. If it doesn’t turn on then there is no current meaning that no electrons are flowing through meaning it cannot conduct electrcity and is not working or not an electrloyte

Question 6

What is an Aqueous Solution?

Answer 6

A solution that has H2O present

Question 7

If the solution is a weak electrolyte will there be a higher yield of H2O or H+ and OH-?

Answer 7

Higher Yield of H2O

Question 8

How to carry out an electrolysis practical?

Answer 8

Half fill a 100cm3 beaker with the solution (Make sure it’s liquid or aqueuos beforehand)

Place Petri Dish over beaker
This should have 2 holes
Now insert Carbon Graphite Rods into these holes (make sure they don’t touch each other because it could cause a short cuircuit)
Next add Crocodile leads to the Rods and connect them to the terminals of a low voltage power supply
Select 4 volts of the power supply and turn it on
Look for bubbling at each electrode (or a coloured coating at Cathode)

test the gas by holding a piece of litmus paper in the solution at that electrode using tweezers

If there is bubbling at both electrodes and you know both hases turn off the cell

If there is not bubbling at Anode or Both leave the cell connected for 5 minutes and then disconnect and study the electrodes for edivence of a metal coating

Question 9

Show the Ionic Half Equation for an OH- ion being dishcharged?

Answer 9

4OH- –> O2 + 2H2O + 4e-

Question 10

In a Hoffman Voltameter would there be more O2 ore more H2 produced?

Answer 10

Double the volume of H2 is produced compared to O2 gas. From the half equations, 4 moles of e- produces 2 moles of H2 but 1 mole of O2

Question 11

What is the test for Hydrogen?

Answer 11

Squeaky Pop Test with lit splint produces a popping sound

Question 12

Test for Chlorine?

Answer 12

Bleahces litmus paper

Turns Litmus Paper Red

Question 13

Test for Oxygen?

Answer 13

Relights glowing splint