1. Balancing Equations LI: To be able to balance simple equations
08/11/2019
Balancing Equations
LI: To be able to balance simple equations
SC: Convert a word equation into a symbol equation
Balance an equation

2. 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.
The conservation of mass in a chemical reaction is an essential prerequisite to understanding why we need to balance equations.

3. Small numbers
The small numbers we sometimes see are called subscripts. O2
This subscript number means there are two oxygen atoms
O O

4. Big numbers The big numbers we sometimes see are called coefficients
This coefficient number means there are two lots of the oxygen molecules
O O
O O

5. One carbon atom and two oxygen atoms react
One carbon atom and two oxygen atoms react. How many atoms are in the product? C O O C

6. C + O2  CO2 C O O C

7. How Will Our See-Saw Look?
C + Cl2  CCl4 Cl C C Cl

8. It’s a Bit Product Heavy
C + 2Cl2  CCl4 Cl C Cl C Cl

9. Now everything balances!
C + 2Cl2  CCl4 Cl C Cl C Cl

10. How will the see-saw look here?
4O2 + S8  8SO2 S O S O

11. 4O2 + S8  8SO2 How can we change this? O S O S O S O S O S O S O S

12. 8O2 + S8  8SO2 O O S = 8 O = 16 O O O O O S O S O O S O S O O S O S O

13. 8O2 + S8  8SO2 O O O S O O S O S O O O S O O S O O S O S O O S S = 8

14. Ag + S8  Ag2S Balance This Equation Ag Ag = 1 S = 8 Ag = 2 S = 1 Ag S

15. Balance These Equations
Fe + H2SO4  FeSO4 + H2 Mg + HNO3  Mg(NO3)2 + H2 Zn + HCl  ZnCl + H2 Extension: When you are done turn these into word equations.