Balancing Equations

When writing a chemical equation, the law of the conservation of mass must be observed in a chemical reaction, the mass of the products equals the mass of the reactants. The # of atoms in the reactants = the # of atoms in the products

Coefficient – the whole number out front of the formula- tells you how many of each molecule Subscript – small number to the bottom right of an element- tells you how many atoms of that element are in the molecule. Ex. 2H2(g) + O2  2H2O

Combustion of Methane Methane gas burns to produce carbon dioxide gas and liquid water Whenever something burns it combines with O2 Write the equation above:

Steps for Writing Equations Use proper formulas for each reactant and product Proper equations should be balanced Count the number of atoms of each element on the reactants side Count the number of atoms of each element on the products side Balance atoms by using coefficients -- Check your work by counting atoms of each element.

Balance by Inspection Polyatomic ions may be counted as one “element” if it does not change in the reaction Al + FeSO4  Al2(SO4)3 + Fe If an element appears in more than one compound on the same side, count each separately and add CO + O2  CO2

Pick an element to balance Use a table if necessary to keep track of your elements Continue to adjust coefficients until balanced. C O C O # # # #