Name: ______________________________________ Date: ________________________
Student Exploration: Balancing Chemical Equations
Vocabulary: coefficient, combustion, compound, decomposition, double replacement, element,
...
Name: ______________________________________ Date: ________________________
Student Exploration: Balancing Chemical Equations
Vocabulary: coefficient, combustion, compound, decomposition, double replacement, element,
molecule, product, reactant, single replacement, subscript, synthesis
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
The scouts are making s’mores out of toasted marshmallows, chocolate, and graham crackers.
1. What is wrong with the image below? There are 4 smores made from 5 marshmallows, 5
graham crackers, and only 3 chocolates.
2. Assuming a s’more requires two graham crackers, one marshmallow, and one piece of
chocolate, how many s’mores could you make with the ingredients shown? 2
Gizmo Warm-up
In a chemical reaction, reactants interact to form products.
This process is summarized by a chemical equation. In the
Balancing Chemical Equations Gizmo, look at the floating
molecules below the initial reaction: H2 + O2 H2O.
1. How many atoms are in a hydrogen molecule (H2)? 1
2. How many atoms are in an oxygen molecule (O2)? 2
3. How many hydrogen and oxygen atoms are in a water
molecule (H2O)? 2 hydrogen and 1 oxygen
4. In general, what does a subscript (such as the “2” in H2) tell you about the molecule?
There are two of the molecules
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5. A chemical equation is balanced if the number of each type of atom on the left side is equal
to the number of each type on the right side. Is this reaction balanced? no
Activity A:
Balancing
equations
Get the Gizmo ready:
Check that the Synthesis reaction is selected and
that all coefficients are set to one. (The
coefficients are the numbers in the boxes.)
Introduction: The equation H2 + O2 H2O is unbalanced because there are two oxygen atoms
on the reactants side of the equation, and only one on the products side of the equation. To
balance the equation, you cannot change the structure of any of the molecules, but you can
change the number of molecules that are used.
Question: How are chemical equations balanced?
1. Balance: Turn on Show histograms. The equation is balanced when there are equal
numbers of each type of atom represented on each side of the equation.
In the Gizmo, use the up and down arrows to adjust the numbers of hydrogen, oxygen, and
water molecules until the equation is balanced. When you are done, turn on Show
summary to check
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