chemical equations & reactions materials: conserving matter
TRANSCRIPT
Chemical Equations & Reactions
Materials: Conserving Matter
Chemical Reaction
Process by which one or more substances are changed into one or more different substances
Indications of a Chemical Reaction
1. Evolution of heat & light
Indications of a Chemical Reaction
2. Production of a gas
Indications of a Chemical Reaction
3. Formation of a precipitate
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 Equation
Reactants Products
Follows the Law of Conservation of Mass
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
Name the number and type of atoms in
AgNO3
(NH4)2CO3
6 H2O
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
Examples
Mg + HCl MgCl2 + H2
Al2(SO4)3 + Ca(OH)2 Al(OH)3 + CaSO4
MgI2 + KNO3 KI + Mg(NO3)2