• What are the symbols for the following elements:
1. Sodium
2. Oxygen
3. Chlorine
4. Iron
5. Copper
• What are the formulas for the following compounds:
1. Water
2. Potassium hydroxide
3. Magnesium oxide
4. Potassium iodide
5. Caesium oxide
Balancing Equations
TBAT balance chemical equations
Key facts
In chemical reactions new substances are made.
A reaction can be summarised in a word equation or a symbol equation.
The total mass of reactants is the same as the total mass of products in a reaction
A symbol equation must be balanced as no atoms are created or destroyed.
State Symbols
• (s)
• (l)
• (g)
• (aq)
• E.g.
1. H2
2. O2
3. CO2
4. H2O
5. C
What is wrong with this equation?
• Lithium was added to water in a school lab. Below is the symbol equation for the reaction – or is it?
Li(s)+ H2O(s) LiO(aq) + H2(g)
http://www.youtube.com/watch?v=8ypUVpwgcAA
Balancing equations
You can never change a formula when balancing an equation. You can only put a number in front of a formula.
Lets consider how to show 2 molecules of CO2:
C2O X
CO4 X
C2O2 X
2CO2
Symbol equations
• No atoms are created or destroyed in a chemical reaction.
• There should be the same number of atoms of each type of element each side of the equation.– Magnesium + Oxygen Magnesium oxide
One carbon atom and two oxygen atoms react.
How many atoms are in the product?
C OO
OCO
C + O2 CO2
C OO OCO
How Will Our See-Saw Look?
C + Cl2 CCl4
Cl
C
Cl
Cl Cl
Cl ClC
It’s a Bit Product Heavy
Cl
C
Cl
Cl Cl
C
C + 2Cl2 CCl4
Now everything balances!
C + 2Cl2 CCl4
Cl
C
Cl
Cl Cl
Cl ClC
Cl Cl
How will the see-saw look here?
4O2 + S8 8SO2
S SS
S S
S
S
S
OO
How can we change this?
4O2 + S8 8SO2
S SS
S S
S
S
S
OO S = 1O = 2
S = 8O = 2
S = 8O = 16
8O2 + S8 8SO2
S SS
S S
S
S
S
OO
OO
OO
OO
OOOO
OO
OO
S = 8O = 2S = 8
O = 16
S = 8O = 16
8O2 + S8 8SO2
S SS
S S
S
S
SOO
OO
OO
OO
OO
OO OO
OO
S = 8O = 16
S = 8O = 16
Balance This Equation
Ag + S8 Ag2S
Ag
Ag = 1S = 8 Ag = 2
S = 1
Balance these equations
1. C + O2 CO2
2. H2 + O2 H2O
3. N2 + H2 NH3
4. CH4 + O2 CO2 + H2O
Fe + H2SO4 FeSO4 + H2
Mg + HNO3 Mg(NO3)2 + H2
Zn + HCl ZnCl + H2
When you are done turn these into word equations.
Balance These Equations
Question sheet
Chemistry
What colour is a strong acid on the
pH scale?
What ions are made by acids and
alkalis?
What colour is an alkali in
phenolphthalein?
When you mix an acid and alkali what do you
make?
Calcium carbonate + nitric acid ->
Potassium oxide + hydrochloric acid ->
Sodium hydroxide + sulphuric acid ->
Define soluble and insoluble
What are the formulas of nitric acid and sulphuric
acid?
Chemistry
Chemistry
Soluble in water Insoluble in water
all common sodium, potassium and ammonium salts
all nitrates
most chlorides silver and lead chloride
most sulfates lead, barium and calcium sulfate
sodium, potassium and ammonium carbonates
most carbonates
sodium, potassium and ammonium hydroxides
most hydroxides
Use the table below to name 3 soluble and 3 insoluble compounds
e.g. sodium nitrate lead carbonate
Bingo
Make a 3x3 grid with some of these symbols
Ag
Ar
Au
CH4
CO2
Cu
Fr
H2
H2O
H2SO4
HCl
HNO3
K
Mg
N2
O2
-OH
Pt
S
Sn
Zn