Balancing Chemical Equations

Balancing Equations

An equation is balanced when the number of atoms of each type is the same on both sides of the equation. Balancing is achieved by placing numbers in front of chemical formulas; the formulas themselves must not be altered.

Equations can include state symbols:

  • (s) = solid

  • (l) = liquid

  • (g) = gas

  • (aq) = aqueous (dissolved in water)

How to Balance an Equation

  1. Count the number of atoms of each type on both sides of the equation.

  2. If the numbers are equal, the equation is balanced.

  3. If the numbers differ, place numbers (coefficients) in front of the formulas to add more of that substance. Do not change the formulas.

    • Hint: Begin with elements that appear in only one substance on each side of the equation.

  4. Continue adjusting coefficients until the equation is balanced.

Example

CH4 + O2 \rightarrow CO2 + H2O

Balancing Equations 1: Questions & Answers

  1. 2Ca+O2→2CaO2Ca + O_2 \rightarrow 2CaO

  2. Na2O + H2O ——>2NaOH

  3. 4Al + 3O2 ——> 2Al2O_3

  4. 2Na + Cl_2 \rightarrow 2NaCl</p></li><li><p></p></li><li><p>Na2CO3 \rightarrow Na2O + CO2</p></li><li><p></p></li><li><p>4K + O2 \rightarrow 2K2O</p></li><li><p></p></li><li><p>C4H8 + 6O2 \rightarrow 4CO2 + 4H_2O</p></li><li><p></p></li><li><p>Fe2O3 + 6HCl \rightarrow 2FeCl3 + 3H2O</p></li><li><p></p></li><li><p>F2 + 2KBr \rightarrow 2KF + Br2</p></li><li><p></p></li><li><p>C5H{12} + 8O2 \rightarrow 5CO2 + 6H_2O</p></li><li><p></p></li><li><p>4NH3 + 5O2 \rightarrow 4NO + 6H_2O</p></li><li><p></p></li><li><p>2HNO3 \rightarrow 2NO2 + H2O + O2</p></li></ol><h4id="56439a1d−bc11−43ca−8f17−fcc8b402b2ad"data−toc−id="56439a1d−bc11−43ca−8f17−fcc8b402b2ad"collapsed="false"seolevelmigrated="true">BalancingEquations2</h4><ol><li><p>Explanationofthebalancedequation:</p></li></ol><p></p></li></ol><h4 id="56439a1d-bc11-43ca-8f17-fcc8b402b2ad" data-toc-id="56439a1d-bc11-43ca-8f17-fcc8b402b2ad" collapsed="false" seolevelmigrated="true">Balancing Equations 2</h4><ol><li><p>Explanation of the balanced equation:</p></li></ol><p>P4(s) + 5O2(g) \rightarrow P4O{10}(s)</p><p>Thisbalancedequationindicatesthatsolidtetraphosphorus(</p><p>This balanced equation indicates that solid tetraphosphorus (P4)reactswithgaseousoxygen() reacts with gaseous oxygen (O2)toproducesolidtetraphosphorusdecoxide() to produce solid tetraphosphorus decoxide (P4O{10}).Specifically,onemoleofsolid). Specifically, one mole of solidP4reactswithfivemolesofgaseousreacts with five moles of gaseousO2toproduceonemoleofsolidto produce one mole of solidP4O{10}.Thestatesymbols(s)and(g)denotesolidandgas,respectively,providinginformationaboutthephysicalstatesofthereactantsandproductsunderthereactionconditions.</p><olstart="2"><li><p>. The state symbols (s) and (g) denote solid and gas, respectively, providing information about the physical states of the reactants and products under the reaction conditions.</p><ol start="2"><li><p>2Mg + O_2 \rightarrow 2MgO</p></li><li><p></p></li><li><p>CaO + 2HCl \rightarrow CaCl2 + H2O</p></li><li><p></p></li><li><p>2P + 3Cl2 \rightarrow 2PCl3</p></li><li><p></p></li><li><p>2SO2 + O2 \rightarrow 2SO_3</p></li><li><p></p></li><li><p>2CO + O2 \rightarrow 2CO2</p></li><li><p></p></li><li><p>C2H4 + 3O2 \rightarrow 2CO2 + 2H_2O</p></li><li><p></p></li><li><p>Fe2O3 + 3CO \rightarrow 2Fe + 3CO_2</p></li><li><p></p></li><li><p>Na2CO3 + 2HCl \rightarrow 2NaCl + CO2 + H2O</p></li><li><p></p></li><li><p>2KMnO4 + 16HCl \rightarrow 2MnCl2 + 2KCl + 5Cl2 + 8H2O$$