Name: ________________________
Balancing Equations Review Homework
Seventh Grade Science – Room 205
Date: _____________ Period: _____
1. What must a balanced equation have before and after the change takes
place?
a. the same number of atoms of each element
b. the same mass
c. both a and b
d. none of the above
2. What do we call the chemical formulas that come before (to the left of) the
arrow in a chemical equation? ___________________
3. What do we call the chemical formulas that come after (to the right of) the
arrow in a chemical equation? __________________
4. How many hydrogen atoms are there in the following chemical formula?
H2O
____________
5. How many hydrogen atoms are there in the following chemical formula ?
2H2O ____________
6. Why were the answers to #4 and #5 different? Explain.
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7. Which chemical formula illustrates 6 Carbon atoms?
a. 3CO2
c. 6C2H12O2
b. 6CO2
d. 2C2O4
How can you be sure you chose the correct answer?
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