Ch.3 - Chemical ReactionsSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Jules Bruno

Under the Law of Conservation of Mass, matter cannot be created nor destroyed and only change form. Balancing a chemical equation ensures this law is followed by having the same number of reactant atoms and product atoms. 


Examining a Balanced Equation 

In a typical balanced equation the numbers in blue are called your coefficients and represent the number of moles for each compound shown. 

Answer-Key-Balanced-Equation-ChemistryCoefficients and Balanced Equation

This written chemical reaction tells us that “2 moles of hydrogen, H­, react with 1 mole of oxygen , O­2 , to produce 2 moles of water, H2O. ” 

The numbers in red are the subscripts and combined with the coefficients give us the number of each particular element. 

Balancing-Equation-InspectionBalanced Chemical Reaction

Balancing a Chemical Equation

Just follow our methods for balancing each of the following chemical equations and you’ll be an expert in no time. 

Balancing-Equations-Worksheet-AnswersUnbalanced Chemical Equations

For all the equations you will need to set up two lists of elements: one for the reactants and another for the products. If your numerical values in both lists don’t match then you’ll have to balance the chemical equation. 


Chemical Equation #1

STEP 1: Set up a list for the elements that are reactants and another list for the elements that are products. The two lists don’t match so we will need to balance the chemical equation. 

Algebraic-BalanceTraditional Balance

STEP 2: Start at the top and going down both lists make sure to balance each element one by one. 

Balancing-carbon-atomsBalancing carbon atoms

STEP 3: Balance the number of carbon atoms by placing a “3” in front of CO­2. The “3” is distributed so the number of carbon and oxygen atoms are both affected. 

Algebraic-Balance-Carbon-atomsAlgebraic Balance (Carbon Atoms)

STEP 4: Continuing down the lists we next balance the number of hydrogen atoms. We do this by placing a “4” in front of H­2O that it distributed to hydrogen and oxygen atom. 

Algebraic-Balance-Hydrogen-AtomsAlgebraic Balance (Hydrogen Atoms)

STEP 5: Finally balance balance the oxygen atoms by placing a “5” in front of O2

Algebraic-Balance-Oxygen-AtomsAlgebraic Balance (Oxygen Atoms)


Chemical Equation #2

STEP 1: Set up your two lists of the elements. Start at the top of the list and work your way down both lists to balance the chemical reaction. 

Unbalanced-Chemical-EquationUnbalanced Chemical Equation

Since both the sodium and chlorine atoms match we continue to the oxygen atoms. 

STEP 2: To balance the oxygen atoms we place a “2” in front of NaClO3 and a “3” in front of O2. This gives “6” oxygen atoms on both sides of the chemical equation.

Algebraic-Balance-Oxygen-AtomsAlgebraic Balance (Oxygen Atoms)

The “2” in front of NaClO3 is also distributed to the sodium (Na) and chlorine (Cl) atoms. This means they will have to be balanced as well. 

STEP 3: To balance the sodium (Na) and chlorine (Cl) atoms we place a “2” in front of NaCl. 

Balanced-Decomposition-EquationBalanced Decomposition Equation 


Chemical Equation #3

At times you will have polyatomic ions (SO42-, NH4+, PO43-) that look the same on both sides of the chemical equation. From the chemical equation we have PO4 on both sides and to make balancing easier just place PO4 in your list of atoms. 

STEP 1: We need to balance the calcium atoms by placing a “3” in front of CaBr2. The “3” will be distributed to both the calcium and bromine atoms in CaBr2

Algebraic-Balance-Calcium-AtomsAlgebraic Balance (Calcium Atoms)

STEP 2: Balance the bromine atoms by placing a “6” in front of LiBr. The “6” will be distributed to both the lithium and bromine atoms. 

Algebraic-Balance-Bromine-AtomsAlgebraic Balance (Bromine Atoms)

STEP 3: Balance the lithium and PO4 atoms by placing a “2” in front of Li3PO4

Algebraic-Balance-Lithium-AtomsAlgebraic Balance (Lithium Atoms)


Chemical Equation #4

STEP 1: The lead (Pb) atoms match so we continue to the oxygen atoms. 

Algebraic-Balance-Lead-AtomsAlgebraic Balance (Lead Atoms)

The lead (Pb) atoms match so we continue to the oxygen atoms. 

STEP 2: Balance the oxygen atoms by placing a “2” in front of H2O. The “2” will be distributed to both the hydrogen and oxygen atoms.

Algebraic-Balance-Oxygen-AtomsAlgebraic Balance (Oxygen Atoms)

STEP 3: Balance the hydrogen and iodine atoms by placing a “2” in front of HI. 

Algebraic-Balance-Hydrogen-Iodine-AtomsAlgebraic Balance (Hydrogen and Iodine Atoms)


Jules Bruno

Jules felt a void in his life after his English degree from Duke, so he started tutoring in 2007 and got a B.S. in Chemistry from FIU. He’s exceptionally skilled at making concepts dead simple and helping students in covalent bonds of knowledge.