Download Balancing Chemical Equations Activity by Liz LaRosa www

Balancing Chemical Equations Activity
by Liz LaRosa
www.middleschoolscience.com
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Objectives :






to read chemical equations
to identify elements by their chemical symbol
to count atoms
to identify the coefficients and subscripts in a chemical equation.
to label the reactants and products of a chemical equation
to balance chemical equations
Materials: These account for one complete set. Color scheme is VERY important for
visualization during the activity.
on 3x5 Index
Cards
2 orange 6's
4 red 2's
2 black 7's
4 blue 3's
2 blue "+"
1 black "yield"
sign --->
1 purple
"Products"
4 green 4's
2 purple 5's
1 red
"Reactants"
on 5x8 Index
Cards
Al
C2H6
H2
Al2O3
CaCl2
H2O NaCl P4O10
C
CO2
CH4
Fe
N2 Na2SO4
Fe3O4 NH3
Na
CaSO4 H2O2 Na2O
O2
P4
Pre Lab Questions:
Answer the following before you begin the activity:
5H2
1. What number represents the Coefficient? _____
2. What number represents the Subscript? _____
3. What element is represented by the letter "H"?
_____
4. How many "H's" do you have? _____
Procedure :
1. Using your set of index cards, replicate the chemical equation onto your desk.
2. Label the reactant side and the product side.
Record the following information into Table 1:
3.
4.
5.
6.
7.
8.
Identify the elements on the reactant side.
Count the number of atoms for each element.
Identify the elements on the product side.
Count the number of atoms on the product side.
Are the 2 sides equal? If not, the equation is not balanced.
The index cards numbered 2 - 7 are your coefficients. They can ONLY be placed in
front of the elements. You can not change the subscripts.
9. Choose an element that is not balanced and begin to balance the equations.
10. Continue until you have worked through all the elements.
11. Once they are balance, count the final number of Reactants and Products.
12. Write the balanced equation.
13. Can your equation be simplified?
Data :
Table 1 : Chemical Equations (whole page, large boxes, sideways into lab book)
Make the following Equations
Reactants
on your desk
Products
Reactants Final
H2 + O2 --> H2O
H2O2 --> H20 + O2
Na + O2 --> Na2O
N2 + H2 --> NH3
P4 + O2 --> P4O10
Fe + H2O --> Fe3O4 + H2
C + H2 --> CH4
Na2SO4 + CaCl2 -->
CaSO4 + NaCl
C2H6 + O2 --> CO2 + H2O
Al2O3 --> Al + O2
Analysis/Results:
1.
2.
3.
4.
5.
What does "-->" mean?
What side of the equation are the reactants found? products?
Why must all chemical equations be balanced?
Why can't the subscripts be changed?
What does it mean to "simplify" the equation?
Conclusion:
2-3 sentences on what you learned.
Products Final
Balanced
Equation
TEACHER NOTES:
The index cards are a bit time consuming to create. I had some students help at lunch time for a
few days. Once done, you can laminate them and have them forever! The materials account for
one complete set which is good for 2-3 students to use.
Print activity cards on card stock instead of making index cards for quicker set up.
The color coding is very important for visualization. It is easier and quicker to locate the
elements that you are trying to balance. If everything is in black ink, its harder to distinguish the
equation contents.
I use this towards the end of my chemistry unit, its a great assessment tool because it involves a
vast amount of abilities that were learned during the chemistry unit. I do the 1st two problems
with the students to guide then through the procedure, and make sure they understand what is
expected. This activity takes about 2 - 3 "45 minute" class periods. I follow up with a worksheet
as a homework assignment.
Make the following
Equations on your desk
H2 + O2 --> H2O
H2O2 --> H20 + O2
Na + O2 --> Na2O
N2 + H2 --> NH3
P4 + O2 --> P4O10
Fe + H2O --> Fe3O4 + H2
C + H2 --> CH4
Reactants
Products
2 hydrogen
2 hydrogen
Reactants - Products Final
Final
4 hydrogen
same as
final
reactants
2 oxygen
1 oxygen
2 oxygen
2 hydrogen
2 hydrogen 4 hydrogen same as
final
reactants
2 oxygen
3 oxygen
4 oxygen
1 sodium
2 sodium
4 sodium
same as
final
reactants
2 oxygen
1 oxygen
2 oxygen
2 nitrogen
1 nitrogen
2 nitrogen
same as
final
2 hydrogen
3 hydrogen 6 hydrogen reactants
4 phosphorus 4 phosphorus 4 phosphorus same as
final
reactants
2 oxygen
10 oxygen
10 oxygen
1 iron
3 iron
3 iron
same as
final
2 hydrogen
2 hydrogen 8 hydrogen
reactants
1 oxygen
4 oxygen
4 oxygen
1 carbon
1 carbon
1 carbon
same as
final
2 hydrogen
4 hydrogen 4 hydrogen reactants
2sodium
1 sodium
2 sodium
1 sulfur
1 sulfur
1 sulfur
4 oxygen
4 oxygen
4 oxygen
1 calcium
1 calcium
1 calcium
2 chlorine
2 carbon
1 chlorine
1 carbon
2 chlorine
4 carbon
Na2SO4 + CaCl2 -->
CaSO4 + NaCl
C2H6 + O2 --> CO2 + H2O
6 hydrogen
2 oxygen
2 aluminum
Al2O3 --> Al + O2
3 oxygen
Balanced
Equation
2 H2 + O2 -->
2 H2 O
2 H2O2 -->
2 H20 + O2
4Na + O2 -->
2 Na2O
N2 + 3H2 -->
2 NH3
P4 + 5O2 -->
P4O10
3Fe + 4H2O -->
Fe3O4 + 4H2
C + 2 H2 -->
CH4
Na2SO4 + CaCl2
-->
same as
final
reactants
CaSO4 +
2 NaCl
same as
2 C2H6 + 7O2 -final
2 hydrogen 12 hydrogen
> 4CO2 + 6H2O
reactants
3 oxygen
14 oxygen
1 aluminum 4 aluminum same as
2 Al2O3 -->
final
4Al + 3O2
reactants
2 oxygen
6 oxygen