Chemical Equations & Reactions Materials: Conserving Matter
Jan 01, 2016
Chemical Reaction
Process by which one or more substances are changed into one or more different substances
Indications of a chemical reaction
4. Change in color. (sumac leaves change color when chlorophyll is destroyed)
Chemical Reactions
There are many ways where matter seems to disappear: The consumption of fuel by your car. The lunch you ate today. The rusting away of your car.
Do they really disappear? NO
Chemical Reactions
Law of Conservation of Matter: in a chemical reaction, matter in neither created nor destroyed; the molecules are merely rearranged atoms are forever! you should be able to account for every individual
atom in a chemical reaction
Word Equation
Represents facts- only qualitative
Example:Methane + oxygen carbon dioxide + water
Writing Chemical EquationsWriting Chemical Equations
Example:
CH4(g) + O2(g) CO2(g) + H2O(g)
(not balanced)
Symbols you will see in equations
Formula Equation
Writing Chemical EquationsWriting Chemical Equations
Inserting Coefficients-small whole # that appears in front of a formula
Multiplies number of atoms of each element indicated in chemical formula
Example:
CH4(g) + 2O2(g) CO2(g) + 2H2O(g)
Balanced Formula Equation
Writing Chemical EquationsWriting Chemical Equations
Atom Inventory
In order to follow the law of conservation-
there must be the same number and type of atoms on both sides of the equation.
Atom Inventory
Is this equation balanced? Take an atom inventory
Mg + O2 MgO yes no
2NaOH Na2O + H2O yes no
Mg + Cl2 MgCl2 yes no
Balancing Chemical Equations
Balance the formula equation according to the law of conservation of mass Balance the different types of atoms one at a
time Balance polyatomic ions that appear on both
sides of the equation as single units Balance H atoms and O atoms after atoms of
all other elements have been balanced