REDOX

Question 1

What is a reaction called when two solutions combine to form an insoluble product?

Answer 1

Precipitation

Question 2

What is the rules for solubility of salts in water?

Answer 2

• Most nitrate salts are soluble
• Most salts containing alkali metals or ammonium ions are soluble
• Most chloride, iodide and bromide salts are soluble excluding Ag, Pb and Hg
  Most sulphate salts are soluble excluding Ba, Pb, Cs and Hg
• Most hydroxides are slightly soluble, NaOH and KOH are the most soluble and Ba, Sr and Ca are slightly soluble
• Most sulphide, carbonate, chromate and phosphate salts are slightly soluble

Question 3

What are oxidation states?

Answer 3

Numbers that help keep track of the loss/gain of electrons

Question 4

What is OILRIG?

Answer 4

Oxidation
Is
Loss
Reduction
Is Gain

Question 5

What is a reducing agent?

Answer 5

A species which loses electrons and is oxidised
Also known as an electron donor

Question 6

What is an oxidising agent?

Answer 6

A species which gains electrons and is reduced
Also known as an electron acceptor

Question 7

How do we write and balance REDOX reactions?

Answer 7

1. Identify the atoms that are oxidised and reduced, using the oxidation number method
2. Balance the half-reaction:
   (i) Make sure that there is the same number of atoms of the element that is oxidised or reduced
   on each side of the half-reactions.
   (ii) If any oxygen is present, balance them by adding water molecules to the other side of the half-
   reaction.
   (iii) If hydrogen atoms are present, balance them by adding hydrogen ions on the other side of the
   half-reaction.
   (iv) Make sure that the half-reactions have the same overall charge on each side by adding
   electrons.
3. If the reaction happens in a basic solution, change any H+ using H2O molecules and then balance
   it using OH- to the opposite side of the equation to balance the oxygens.