Word Equations Millions of chemical reactions take place everyday The conversion of food you eat from food into chemical energy Plants undergoing photosynthesis to create their own energy

Many reactions don’t involve life The energy your car obtains from the battery to start your car is a chemical reaction Metal rusting is a chemical reaction

As you can see it is very important that you understand chemical reactions

In a chemical reaction bonds are broken and reattached to form new chemical compounds When dealing with chemical reactions you must always consider the law of conservation of mass

In a chemical reaction mass is neither lost nor gained Just as much product will be made as reactants that reacted Just think of a chemical reaction as a rearrangement

Chemical Equations Rusting Word Equation –I–Iron + Oxygen  Iron (III) Oxide Chemical Equation –F–Fe + O 2  Fe 2 O 3

Fe (s) + O 2 (g)  Fe 2 O 3 (s) You can also indicate which physical state a substance is in –S–Solid (s) –L–Liquid (l) –G–Gaseous (g) –A–Aqueous Solution (aq)

Chemical Reactions Most chemical reactions will use a catalyst A catalyst is either an element or a compound which speeds up the chemical reaction –I–It is not used in the reaction –I–It is written above the arrow of the chemical reaction

Symbols Used in a Chemical Equation  3. 4.(s) 5.(g) 6.(l) 7.(aq) Separates the reactants or products from each other 2.Separates the reactants and products 3.Reversible Reaction 4.Solid State of Matter 5.Gaseous State of Matter 6.Liquid State of Matter 7.Aqueous Solution 8.Heat is supplied 9.Heat is supplied 10.Indicates which Catalyst has been used Heat Pt

Balancing Chemical Equations Frame + Wheel + Handlebar + Pedal = Bicycle Will this make a bicycle? No Why not? A bicycle has 2 wheels and 2 pedals So the correct formula for a bicycle is Frame + 2 Wheels + Handlebar + 2 Pedals = Bicycle This is called a Balanced Equation

A balanced equation occurs when all reactants equal all the products H CO 2  C 6 H O 2

Rules for Balancing Equations 1.Determine the correct formula for all the reactants and products in the reaction 2.Write the formulas for the reactants on the left and formulas for the products on the right 3.Count the number of atoms of each element in the reactants and products 4.Balance the elements one at a time by using coefficients, when no coefficient is written assume it to be 1 5.Double check everything to be sure 6.Make sure you have the lowest number combination possible