1.56 recall that one faraday represents one mole of electrons

One Faraday is 96500 coulombs. That is the amount of coulombs in one mole of electrons.

1.57 calculate the amounts of the products of the electrolysis of molten salts and aqueous solutions

One faraday is 96500 coulombs. It is also one mole of electrons.

If current of 0.2 Apms is passed through copper(ll) sulphate for tow hours, how much copper do you get?

• Write out the half equation

Cu2+ + 2e > Cu

• Work out coulombs of electrons flowing

Coulombs= current x time
Q= IT

time is 2x60x60 (times 60 makes minutes, times 60 again makes it seconds)

Q= 0.2 x 7200= 1440 coulombs

• Convert C into moles of electrons

Moles= C/Faraday

Mol= 1440/96500

Mol= 0.015

• Work out scale factor

Cu2+ + 2e > Cu

For every 2 moles of electrons, there will be one Cu

Sf= Moles of product/ moles of electrons

Sf= 1/2

Sf= a half

• Work out moles of product using Scale factor

so we do the moles of electrons times the scale factor

0.015x1/2= 0.0075 Moles of Cu

• Convert moles into mass

Moles x Mr

0.0075 x 63.5= 0.48g of copper

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

At the positive electrode, electrons will be lost: to show this we write the lost electrons as products:
2Br- > Br2 + 2e-
Make sure the charges are equal on both sides: 1- > 1-.

At the negative electrode, electrons will be gained so we write them as reactants:
2H+ + 2e- > H2
And to make sure the charges are the same on both sides: 0 > 0.

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 (ones that wont react) into an aqueous solution.

At the positive electrode the negatively charged ion from the compound will form an atom. At the negative electrode the atom of the positive ion will form.

sodium chloride: Hydrogen at the negative; chlorine at the positive
copper(II) sulfate: copper at the negative; oxygen at the positive
dilute sulfuric acid: Hydrogen at the negative; oxygen at the positive

If the metal in the solution is more reactive then hydrogen, the hydrogen from the water will be a product, as the metal will bond with the oxygen.

Test the products using known methods: eg damp blue litmus paper turned red by chlorine.

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

Inert electrodes are ones that don't react with any other substances, but only play a role in the transfer of electrons.

To describe an experiment you need to be able to draw and label an electrolysis experiment. As an example:

figurepool.com

Lead bromide will make lead and bromine, you can use chemical tests to see is you got these products from electrolysis.

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

In electrolysis ionic compounds conduct electricity. Positively charged ions move to one end, negatively to the other, these are then turned into atoms (by losing their charge) and so new substances are formed.

1.51 describe experiments to distinguish between electrolytes and nonelectrolytes

Set up an electric circuit with an LED and a break in the wire, put both ends of wire into a solution/molten substance. If the LED lights up then there is a current flowing, this will only be able to happen if the solution is conducting: so it must be an electrolyte. Conversely if the LED does not light up then there is no current flowing, and so the solution has not conducted electricity meaning it must be a nonelectrolyte.

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

When ionic compounds are molten or in solution, the positive and negative ions separate  this means that there are ions free to flow, and so they can conduct electricity.

1.49 understand why covalent compounds do not conduct electricity

In covalent compounds there are no electrons free to move, this means there can be no transfer of electricity through a covalent compound

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

An electric current is a flow of electrons, although it can also be a flow of ions (as they have a charge.)