The document discusses relationships derived from a balanced chemical equation. It states that coefficients in a balanced equation represent the numbers of individual particles and moles of particles, indicating mole ratios between reactants and products. Stoichiometry relies on the law of conservation of mass, where the mass of reactants equals the mass of products. Mole quantities can be converted to mass by multiplying by the molar mass to determine the mass relationships between substances in a chemical reaction.

2. Objectives
Describe the types of relationships
indicated by a balanced chemical
equation.
State the mole ratios from a balanced
chemical equation

3. Rally coach:
 Balance the following chemical equation
Partner A ;
 H2 + O2 = H2O
 Partner B :
 Mg +Cl2 = Mg Cl2

4. Stoichiometry
 Stoichiometry: The study of quantitative
relationships between the amounts of reactants used
and amounts of products formed by a chemical
reaction
 Stoichiometry is based on the law of conservation of
mass. Which states that states that matter is neither
created nor destroyed in a chemical reaction

5.  In any chemical reaction, the amount of matter
present at the end of the reaction is the same as the
amount of matter present at the beginning. Therefore,
the mass of the reactants equals the mass of the
products.
 Amounts of reactants = Amounts of products

6. Relationships Derived From A
Balanced Chemical Equation
 The balanced chemical equation for the following
chemical reaction
 ….Fe(s) + …. O 2 (g) → …. F e 2 O 3 (s)
 4Fe(s) + 3 O 2 (g) → 2F e 2 O 3 (s)
 the coefficients in an equation represent
1- numbers of individual particles
2- numbers of moles of particles.
 Therefore, you can also say that four moles of iron react
with three moles of oxygen to produce two moles of
iron(III) oxide.

8. Converting mole to mass
However, by converting
the known mole
quantities to mass, the
mass relationships
become clear.
Remember :
The chemical equation does not directly tell you
anything about the masses of the reactants and
products
moles are converted to
mass by multiplying by
the molar mass.

9. So the mass of the reactant
is calculated as follows
4Fe(s) + 3 O 2 (g) → 2F e 2 O 3 (s)
we have two reactants
1- 4 mol Fe
 multiplying by the molar mass. ( from
the periodic table )
2- 3 mol O 2
multiplying by the molar mass. ( from
the periodic table )

10. Now, total mass of the reactant is
given by
 The total mass of the reactants is:
 (………. + ………… ) = ………… g
 Similarly, the mass of the product is
calculated as follows:
 2 mol F e 2 O 3
 Note that the mass of the reactants equals
the mass of the product.

12. Mole ratio
A mole ratio: is a ratio between the numbers of
moles of any two of the substances in a balanced
chemical equation

13. So , for the following chemical equation
 2K(s) + B r 2 (l) → 2KBr(s)
 the mole ratios are