2. Chemical reactions are occurring around us all the time
Food cooking
Fuel being burned in a car’s engine
Oxygen being used in the human body

3. To describe the reaction that creates fire at the bunsen burner in lab:
Methane gas reacts quickly with oxygen gas to produce fire, carbon dioxide, and water vapor
That’s a lot to write!

4. We can simplify the description of our reaction by using a word equation:
Methane gas + oxygen gas →
fire + carbon dioxide gas + water vapor
Still a lot to write!

5. The simpler way to express a chemical reaction is to use formula equations:
CH4 + O2 → CO2 + H2O
However there is some information that is not shown in the formula equation:
– State of matter
– Fire/ Energy

6. We can show state of matter using the following symbols:
(s) solid
(l) liquid
(g) gas
(aq) aqueous solution
(substance is dissolved in water)
CH4 (g)+ O2 (g) → CO2 (g) + H2O (g) energy

7. Is the equation balanced?
CH4 (g)+ O2 (g) → CO2 (g) + H2O (g) energy
CH4 (g)+ 2O2 (g) → CO2 (g) +
2H2O(g) + energy

8. Practice writing these equations:
Hydrogen plus oxygen yields water H2 + O2 → H2 O Nitrogen plus hydrogen yields ammonia N2 + H2 → NH3 Aluminum bromide plus chlorine yields aluminum chloride and bromine AlBr3 + Cl2 → AlCl3 + Br2

9. Balance and include state of matter:
2H2 (g) + O2(g) → 2H2 O(l) N2 (g) + 3H2(g) → 2NH3(g) 2AlBr3(s) + 3Cl2(g) → 2AlCl3(s) + 3 Br2(l)

10. Nitrogen plus oxygen gas react and form dinitrogen pentoxide 2N2(g) + 5O2 (g) → 2N2 O5 (g)

12. There are five general types of reactions: Decomposition
Synthesis
Decomposition
Single-replacement
Double-replacement
Combustion

14. Decomposition Reaction
A reaction where a compound breaks down into two or more simpler products

15. Single Replacement Reaction
A single-replacement reaction is one in which one element replaces a second element in a compound

16. Double Replacement Reaction
AB CD = AD CB
A double-replacement reaction is a reaction involving an exchange of positive ions between two compounds

18. Combustion Reaction CH4 + 2O2 → CO2 + 2H2O + energy
A combustion reaction is a reaction in which an element or a compound reacts with oxygen, to form an oxide and heat
Hydrocarbons combust with oxygen to form carbon dioxide and water.