Balancing equations

1
Balancing equations
2
Formulae of compounds..

• What are the formulae for these compounds?
• Water
• Carbon dioxide
• Methane
• Hydrochloric acid
• Sulphuric acid

H2O CO2 CH4 HCl H2SO4
3
Word equations

• The reactants and products are represented as
  words
• Nitrogen Hydrogen ? Ammonia

4
Symbol equations

• The reactants and products are represented by
  their formulae
• Nitrogen Hydrogen ? Ammonia
• N2 H2 ? NH3

5
Balancing the equations

• The number of atoms of each element on each side
  of the arrow has to be the same
• N2 H2 ? NH3
• 2 nitrogens 1 nitrogen
• 2 hydrogens 3 hydrogens

6

• Balance the nitrogens first
• N2 H2 ? 2NH3
• Then balance the hydrogens
• N2 3H2 ? 2NH3
• Double-check the answer
• N2 3H2 ? 2NH3
• 2 nitrogens 2 nitrogens
• 6 hydrogens 6 hydrogens

BALANCED
7
Have a go at balancing these

• Ca O2 ? CaO
• H2SO4 KOH ? K2SO4 H2O
• H2 NO ? H2O N2
• Fe2O3 CO ? Fe CO2

8
Relative atomic mass

• Each element has a mass.
• It is found on the periodic table (the larger of
  the two numbers)
• For example
• Carbon is 12
• Oxygen is 16

9
Relative molecular mass

• By using the mass of each element, we can find
  out the total mass of a compound
• Water H2O
• H 1
• O 16
• Water (2 x 1) (1 x 16) 18g

10
What are the masses of these compounds?

• H2SO4 Sulphuric acid
• CaCl2 Calcium chloride
• KNO3 Potassium nitrate
• NH4NO3 Ammonium nitrate
• NaHSO4 Sodium sulphate
• MgCl2 Magnesium chloride
• CuCO3 Copper carbonate
• Ca(NO3)2 Calcium nitrate

11
(No Transcript)