Balancing Chemical Equations

Fundamentals of Chemical Equations

• Chemical equations describe chemical processes by placing reactants on the left and products on the right of a reaction arrow ($\rightarrow$).

• Equations must be balanced so that the same number of atoms of each element exists on both sides of the reaction.

• Subscripts indicate the number of atoms of an element present in one molecule.

• Coefficients are numbers placed before chemical formulas to indicate the total number of molecules needed to balance the equation.

Rules for Balancing Equations

• Balance elements one at a time.

• Begin with an element present in only one compound on each side of the equation.

• If an element exists by itself in elemental form, balance it last.

• Adjust coefficients systematically until all atom counts match on both sides.

Example Walkthrough: Propane Reaction

• Carbon ($C$): Propane ($C_3H_8$) has $3$ carbon atoms, requiring a coefficient of $3$ for carbon dioxide ($3\,CO_2$).

• Hydrogen ($H$): Propane ($C_3H_8$) has $8$ hydrogen atoms, requiring a coefficient of $4$ for water ($4\,H_2O$).

• Oxygen ($O$): The product side contains $10$ total oxygen atoms ($6$ from $3\,CO_2$ and $4$ from $4\,H_2O$), requiring a coefficient of $5$ for diatomic oxygen gas ($5\,O_2$).