1.55 Write ionic half-equations representing the reactions at the electrodes during electrolysis

At positive (anode) electrode, electrons are lost.
eg 2Br- > Br2 + 2e-

At negative (cathode) electrode, electrons are gained.
eg 2H+ + 2e- > H2

*Make sure charges are the same on both sides!!

1.54 Describe experiments to investigate electrolysis, using inert electrodes, of aqueous solutions such as sodium chloride, copper(II) sulfate and dilute sulfuric acid and predict the products

• Place inert electrodes in aqueous ionic solution
• At positive electrode (anode), - ion will form an atom (non metal) 
• At negative electrode (cathode), + ion will form an atom (metal)

eg

• Sodium chloride: sodium at cathode, chlorine at anode
• Copper(II) sulphate: copper at cathode, oxygen at anode, sulphur stays in solution
• Sulphuric acid: hydrogen at cathode, oxygen at anode, sulphur stays in solution

To help remember:

CINDY IS NOT AN INDECENT POTATO:

Cathode

Is

Negative

Anode

Is

Positive

NAP MAN:

Non-metal

At

Positive

Metal

At

Negative

CCOASS (for copper(II) sulphate)

(Cathy Chopped Apples And Stabbed Sue)

Copper

Cathode

Oxygen

Anode

Sulphur

Solution

HCOASS (for dilute sulphuric acid)

(Henry Cut Onions And Started Sulking)

Hydrogen

Cathode

Oxygen

Anode

Sulphur

Solution

1.53 Describe experiments to investigate electrolysis, using inert electrodes, of molten salts such as lead(II) bromide and predict the products

Figure 1

• Set up the apparatus in figure 1
• The lead (metal) will be attracted to the negative cathode where it will gain electrons
• The bromine (non metal) will be attracted to the positive anode where it will lose electrons
• Lead and bromine formed
• Yay

Inert electrodes don't react with other substances - only play a role in electron transfer and you need to be able to draw that apparatus. Good luck, padawan.

1.52 Understand that electrolysis involves the formation of new substances when ionic compounds conduct electricity

Ionic compounds conduct electricity when molten or in solution. During electrolysis, positively charged ions move to one side (cathode, which is the negatively charged electrode) and form metals. The negatively charged ions move to the other side (anode, the positively charged electrode) to form non metals. This is because opposite charges attract. These ions become atoms / new products because they undergo a reaction where either a gain or loss of electrons occurs.

TO REMEMBER:
Cathode
Is
Negative
Anode
Is
Positive

Cindy Is Not An Indecent Potato

1.51 Describe experiments to distinguish between electrolytes and non-electrolytes

• Set up a circuit with an LED light, a battery/power pack, wire and a solution
• Create a gap between the two ends of the wire. Place them in the solution.
• Switch the power pack on (if required)
• If LED lights up, a current is flowing through the molten substance / solution. This means it is an electrolyte.
• If it doesn't light up, there's no current, therefore it is not an electrolyte.

Or you could just...

1.50 Understand why ionic compounds conduct electricity only when molten or in solution

When in solution, ions separate (to form + and - ions, accordingly) and they become free to move, so they can carry electricity and so the compound can now conduct when it is molten / in solution.

1.49 Understand why covalent compounds do not conduct electricity

In covalent substances, the electrons are not free to move, so current can't move through the substance; there's no electrons to carry it - no transfer of electricity.

1.48 Understand that an electric current is a flow of electrons or ions

Surprise! An electric current is a flow of electrons or ions. Well done, me. 

5.2 Describe and explain the extraction of aluminium from PURIFIED aluminium oxide by electrolysis..

..including:
i. the use of molten cryolite as a solvent and to decrease the required operating temperature
ii. the need to replace positive electrodes
iii. the cost of electricity as a major factor

The extraction
1. Bauxite purified into aluminium oxide
2. Dissolved in molten cryolite - this is an aluminium compound and brings down the boiling point (less electricity needed = less energy needed = less cost). Also a solvent for Al2O3
3. At the negative electrode, aluminium is formed.
4. Oxygen forms at the positive electrode
5. Oxygen reacts with the positive graphite anode and it becomes corroded so it needs to be replaced frequently.

The electricity needed in this process costs a lot of money, so the process tries to use as little electricity as possible (which is a lot, to be honest)

Little key notes

• Formula for aluminium oxide: Al2 O3 (numbers in subscript)
• Equation for this is 2Al2 O3 (l) ---> 4Al (l) + 3O2 (g) (numbers in red are used to balance the equation)
• It forms the ions Al 3+ (which is the cathode [-]  ) and O 2- (which is the anode [+])
• Aluminium normally melts at about 2000 degrees C but in cryolite, it melts at about 900 degrees C
• Uses include aircraft construction (it's low density + strong), cans for drinks (easy to shape + corrosion resistant) and boilers and cookers (good heat conductor)
• An ionic compound will only be able to conduct electricity if it is molten or in an aqueous solution.
• Walls of the thingie (see below) are the negative anodes.
• For electricity to flow, there must be either delocalized electrons or ions that are able to move.

Here's a little diagram I drew that looks kind of depressing but hey, I tried.

Figure 1

See key word quizlet - link on the right hand side menu.