(2.3) Balancing Chemical Equations (p150). Conservation of Mass As we saw in class, the mass of the...

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(2.3) Balancing Chemical Equations (p150)

Transcript of (2.3) Balancing Chemical Equations (p150). Conservation of Mass As we saw in class, the mass of the...

Page 1: (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.

(2.3) Balancing Chemical Equations

(p150)

Page 2: (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.

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.

Page 3: (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.

How To Write a Balanced Chemical Equation

1. The chemical formula for a substance CANNOT be changed!ex. CO2 molecules must stay as CO2

Page 4: (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.

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

Page 5: (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.

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.

     

Page 6: (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.

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.

Page 7: (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.

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

Page 8: (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.

TRY THESE Worksheets 2.3 (D) and 2.3

(E)

Page 9: (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.

(2.3) Balancing Chemical Equations

(p150)

Page 10: (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.

ASSIGNMENTS: Workbook p56 p60-63