Name ______________________________ Class ___________________ Date __________________
Quick Lab
DATASHEET
Balancing Chemical Equations
MATERIALS
For each group
• Legos, 4 colors
INTRODUCTION: SEE BOOK, P. 225
Chemical reactions are balanced when the type and number of elements on the
reactant side of the equation, is identical to the type and number of elements on the
product side of the equation. See p. 225 for an example. Sometimes, in order to
balance a reaction, you have to “add in” more molecules or compounds or reactants
or products.
PURPOSE
You will use these Legos to make models of balanced chemical equations for the
following chemical reactions:
a. H2 + Cl2  HCl
b. H2 + O2  H2O
c. Ca + H2O  Ca(OH)2 + H2
PROCEDURE
1. In your bag, you have four colors of Lego. You have one calcium, two
chlorines, four oxygens, and ten hydrogens. Decide which Lego color
represents each element, and make a color key. Record this key on your
datasheet.
2. Use the Legos to build the products for the first reactant.
3. Rearrange the atoms of the reactants to form the products. Rules:
a. You must use all of the reactant Legos in forming the product (no leftovers allowed!)
b. You may need different amounts of some of the reactant compounds. (In
other words, you can increase the amount of the reactant Legos, as long as you
add in entire “molecules”, not just individual “elements”.)
4. Once you have balanced products and reactants, redo the procedure, but sketch
the products and reactants on your data sheet
Grading scale: 16 points
(2 for the color key, 2 for each product, 2 for each reactant)
A: 14-16 B: 13 C: 11-12
D: 10 F: <10
Name ______________________________ Class __________________ Date __________________
Color Key
REACTION
Calcium
Chlorine
Oxygen
REACTANTS
H2 + Cl2  HCl
H2 + O2  H2O
Ca + H2O  Ca(OH)2 + H2
Grading scale: 16 points
(2 for the color key, 2 for each product, 2 for each reactant)
A: 14-16 B: 13 C: 11-12
D: 10 F: <10
→
PRODUCTS
Hydrogen
Name ______________________________ Class __________________ Date __________________
Grading scale: 16 points
(2 for the color key, 2 for each product, 2 for each reactant)
A: 14-16 B: 13 C: 11-12
D: 10 F: <10