1. Chemical Reactions

2. Chemical Reactions
In chemical reactions, one or more substances change into different substances.

3. Representing Chemical Reactions
Chemists use equations to describe chemical reactions:
Word equations show the name of the materials in the chemical reaction.
Chemical equations show the chemical formulas of the materials in the chemical reaction.
Reactants: substances that are used up during a reaction; starting substances
Products: substances that are produced during a reactions; ending substances
REACTANT(S)  PRODUCT(S)
(Starting materials) (yields) (ending materials)
(forms)
(produces)

4. Common State Symbols in Chemical Equations
Meaning
Example
(s)
Solid
Sodium chloride, NaCl(s)
(l)
Liquid
Bromine, Br2(l)
(g)
Gaseous
Hydrogen, H2(g)
(aq)
Aqueous (dissolved in water)
Aqueous sodium chloride solution, NaCl(aq)

5. Example #1
Word equation: sodium + chlorine  sodium chloride Chemical equation: Na(s) + Cl2 (g)  NaCl(s)

6. Example #2
Word equation: zinc + copper (II) sulphate  zinc sulphate + copper + energy Chemical equation: Zn(s) + CuSO4 (aq)  ZnSO4 (aq) + Cu(s) + energy
zinc
Copper (II) sulphate
Zinc sulphate
copper

7. Consider the following reaction:
AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq)
Name the reactants and products in this reaction.
Name the chemicals that are dissolved in water.
Name the white solid.
What physical properties do both reactants have in common?

8. Homework
Worksheets:
“Practice: Write the Word Equation” #1-6