What is the Relative Formula Mass for MgCl2?
24 + (35.5 * 2) = 95
What does it mean if a salt is Anhydrous?
Salt doesn’t contain any water of crystallisation
What does it mean if a salt is Hydrated?
A salt contains water of crystallisation
What is Electrolysis?
- Breaking down of a substance using electricity
- Electric current passed through electrolyte causing it to decompose
- Oxidation and reduction occur
What is Oxidation?
Loss of electrons
What is Reduction?
Gain of electrons
What are Ionic Half Equations?
Show how electrons are transferred during reactions
How do you Write Half Equations?
- Put 1 thing as being oxidised/reduced on one side of arrow, the thing it gets oxidised it reduced to on the other
- Balance up number of atoms
- Add electrons (e^-) onto one side to balance up charge
What are Molten Ionic Compounds?
- Electrolysed because ions move freely
- Broken into their elements
- E.g. molten lead bromide (PbBr2)
How do you sort up an Electrochemical Cell for an Aqueous solution?
- Get 2 inert electrodes (graphite or platinum electrodes)
- Clean surface of electrode using emery paper (or sandpaper)
- Place electrodes into beaker filled with your electrolyte
- Connect electrodes to power supply using wires and crocodile clips
- Turn power supply on and a current will flow through cell
What is an Electrochemical Cell?
- Circuit
* Made up of: anode, cathode, electrolyte, power source, wires that connect 2 electrodes
How can you reduce a Metal Oxide (copper II oxide) to find its Empirical Formula?
- Place bung into test tube with hole at end, weigh using balance
- Take bung out and put copper(II)oxide in middle of tube
- Put bung in and weigh again
- Use Bunsen burner to heat copper(II)oxide until changes colour from black to pink
- Turn of heat and leave to cool
- One cooled, weigh test tube with bung and contents
How can you find the Empirical formula using Combustion?
- Heat crucible to get it clean
- Cool it then weigh it (initial)
- Add magnesium ribbon,reweigh
- Mass of magnesium is this reading minus initial reading
- Heat crucible until magnesium turned white, lid on, leave small gap so oxygen can enter
- Cool it then reweigh
- Mass of magnesium oxide is this reading, minus initial reading
