In this lesson our instructor talks about chemical reactions. First, he discusses the law of conservation of mass and balancing chemical reactions. Then he talks about balancing chemical reaction, chemical equilibrium, electrolytes and nonelectrolytes. He also lectures on predicting the product of an aqueous reaction through single-replacement, and double-replacement. He ends the lesson with a summary and two helpful sample problems. Chemical Reactions The need to balance chemical reactions follows from the law of conservation of mass. Electrolytes or electrolytic solutions contain free ions in solution. Strong electrolytes dissociate completely, while weak electrolytes hardly ionize. When predicting if a precipitate will form during an aqueous reaction, it is useful to refer to a table of solubility rules. A net ionic equation only shows the formation of the nonaqueous species from its constituent ions.