(2.3) Balancing Chemical Equations (p150). Conservation of Mass As we saw in class, the mass of the...
-
Upload
jacob-fletcher -
Category
Documents
-
view
213 -
download
0
Transcript of (2.3) Balancing Chemical Equations (p150). Conservation of Mass As we saw in class, the mass of the...
(2.3) Balancing Chemical Equations
(p150)
Conservation of Mass
As we saw in class, the mass of the reactants must equal the mass of the products in a chemical reaction.
To show that a reaction is balanced, we must write a balanced chemical equation.
In a balanced chemical equation, the number of atoms on each side of the equation is the same.
How To Write a Balanced Chemical Equation
1. The chemical formula for a substance CANNOT be changed!ex. CO2 molecules must stay as CO2
How To Write a Balanced Chemical Equation
2. From the word equation, write the chemical equation using the correct chemical formula for all the substances involved.
ex. The combustion of ethanol (C2H6OH)
ethanol+ oxygen carbon dioxide + water
C2H6OH + O2 CO2 + H2O
How To Write a Balanced Chemical Equation3. Count the number of atoms in both the reactants and
products.4. Multiply each formula by a coefficient to balance the
number of each kind of atom in both the reactants and products.
THE RAP SHEET
The RAP sheet is a methodology used to help balance chemical equations.
It helps keep track of the number and kinds of atoms in a chemical equation.
RReactants
AAtoms
PProducts
C
H
O
2
6
3
C2H5OH + O2 CO2 + H2OAdd coefficient 2 CO2
Add coefficient 3 to H2OAdd coefficient 3 to O2
1
2
3
2
5
6
77
TRY THESE Worksheets 2.3 (D) and 2.3
(E)
(2.3) Balancing Chemical Equations
(p150)
ASSIGNMENTS: Workbook p56 p60-63