STARTER Try to name the following compounds You have 5 minutes!
H NO 3 Zn Cl 2 H 2 SO 4 Cu Cl 2 Ca (OH) 2 Ca CO 3 Ag BrNa OH Ag 2 OCa SO 4 Cu OMg O Ag NO 3 H Cl Na 2 SO 4 Na Cl
Balancing Equations Everyone should: Be able to balance simple equations Most people will: Balance equations using compounds like OH - NO 3 - SO 4 2- Some people will: Be able to balance equations with unusual compounds
The law of conservation of matter ATOMS CANNOT BE CREATED OR DESTROYED! The idea of the famous scientist John Dalton in 1700's.
Hydrogen + chlorine hydrogen chloride H 2 + Cl 2 HCl Remember: Hydrogen and Chlorine are diatomic + REACTANTS 2 H atoms 2 Cl atoms PRODUCTS 1 H atom 1 Cl atom This is impossible as it implies that atoms have been destroyed.
What do we do? We need to make the number of atoms equal on both sides of the equation, in order to get the equation to BALANCE. Equation is now balanced, as there are the same number hydrogen atoms (2) and the same number of chlorine atoms (2) on the products and reactant side.
Firstly you need an equation with the correct “formulae” You’ll probably be given this in the question Just like this one Mg + O 2 MgO Then all you do is list the atoms that are involved on each side of the arrow Mg + O 2 MgO Mg O
[1] Just count up the atoms on each side Then start balancing: Mg + O 2 MgO 2 The numbers aren’t balanced, so make your adjustments: And adjust totals Mg + O 2 MgO 2 Mg 1 O 2O Mg 1 Mg 2 O 2O 2
Mg + O 2 MgO 2 But the numbers still aren’t equal 2 And adjust totals again NOW BOTH SIDES HAVE EQUAL NUMBERS OF ATOMS WE SAY THAT THE EQUATION IS BALANCED!! 2
GROUP ACTIVITY: Try to balance these equations You have 5 minutes! [1] Na + Cl 2 NaCl [2] CH 4 + O 2 CO 2 + H 2 O [4] Al + O 2 Al 2 O 3 [3] Li + HNO 3 LiNO 3 + H 2 Why didn’t anyone tell me it was so easy to balance equations???!!!
How did you get on?? [1] 2 Na + Cl 2 2 NaCl [2] CH O 2 CO H 2 O [4] 4 Al + 3 O 2 2 Al 2 O 3 [3] 2 Li + 2 HNO 3 2 LiNO 3 + H 2 Here are the answers:
Examples It’s best to balance using whole numbers