Download Review Sheet

4.02 – Balancing Equations Lesson Review
1. Define reactants.
2. Define products.
3. Define chemical equation.
4. What do each of the following symbols mean in a chemical equation?
a. s
b. l
c. g
d. aq
5. Define Law of Conservation of Mass.
6. What do we change in a chemical equation to balance them?
7. What are six tips to balancing equations?
8. Balance the following equations.
a. NaCl + F2  NaF + Cl2
b. P + O2  P2O5
c. C3H8 + O2  CO2 + H2O
d. AlBr3 + K2SO4  KBr + Al2(SO4)3
4.02 – Balancing Equations Lesson Review Key
1. Define reactants. The substances that are present at the beginning and undergo a
chemical reaction.
2. Define products. The new substances that are formed or produced by a chemical
reaction.
3. Define chemical equation. A representation, using formulas and symbols, of a
chemical reaction.
4. What do each of the following symbols mean in a chemical equation?
a. s = solid
b. l = liquid
c. g = gas
d. aq = aqueous
5. Define Law of Conservation of Mass. Matter is neither created nor destroyed
during an ordinary physical change or chemical reaction.
6. What do we change in a chemical equation to balance them? coefficients
7. What are six tips to balancing equations?
a. Balance each type of element one at a time.
b. Whenever you add a coefficient in front of a formula, remember that it
affects the number of each atom in that formula.
c. Sometimes an element is found in more than one compound on the same side
of an equation, which can make it even more challenging to balance.
d. There are times when you may have to change a coefficient more than once
before the entire equation is balanced, so work with a pencil with an eraser.
e. If a polyatomic ion appears on both sides of the equation, you can balance
the ion as if it is a single unit.
f. Always remember to check and check again!
8. Balance the following equations.
a. 2NaCl + F2  2NaF + Cl2
b. 4P + 5O2  2P2O5
c. C3H8 + 5O2  3CO2 + 4H2O
d. 2AlBr3 + 3K2SO4  6KBr + Al2(SO4)3