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Objectives. To be able to write a balanced equation for a chemical reaction. Pb(NO 3 ) 2 (aq) + 2NaI (aq) PbI 2 (s) + 2NaNO 3 (aq). A chemical reaction is balanced by using a systematic approach:. Write the formulas of the reactants and products to give the unbalanced chemical equation.
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Objectives • To be able to write a balanced equation for a chemical reaction Pb(NO3)2 (aq) + 2NaI (aq) PbI2 (s) + 2NaNO3 (aq)
A chemical reaction is balanced by using a systematic approach: • Write the formulas of the reactants and products to give the unbalanced chemical equation. • Balance by trial and error starting with the most complicated molecule(s). Leave pure elements to the end. • At the end check to be sure the equation is balanced (same numbers of all types of atoms on the reactant and product sides).
Example: • Hydrogen gas and oxygen gas combine to form liquid water. • Write the formulas of the reactants and products to give the unbalanced chemical equation. H2(g) + O2(g) H2O(l)
Example: • Hydrogen gas and oxygen gas combine to form liquid water. • At the end check to be sure the equation is balanced (same numbers of all types of atoms on the reactant and product sides). 2H2(g) + O2(g) 2H2O(l)