The following are actual student responses to the question: Why is it necessary to balance chemical equations? a. The chemicals will not react until you have added the correct mole ratios. b. The correct products will not be formed unless the right amount of reactants have been added. c. A certain number of products cannot be formed without a certain number of reactants. d. The balanced equation tells you how much reactant you need and allows you to predict how much product you’ll make. e. A mole-to-mole ratio must be established for the reaction to occur as written. Justify the best choice, and for choices you did not pick, explain what is wrong with them.

Let's go through each response and analyze them individually: a. The chemicals will not react until you have added the correct mole ratios. b. The correct products will not be formed unless the right amount of reactants have been added. c. A certain number of products cannot be formed without a certain number of reactants. d. The balanced equation tells you how much reactant you need and allows you to predict how much product you’ll make. e. A mole-to-mole ratio must be established for the reaction to occur as written.

Based on the evaluation done in Step 1, we can conclude that the best choice is: d. The balanced equation tells you how much reactant you need and allows you to predict how much product you’ll make. The main purpose of balancing a chemical equation is to comply with the law of conservation of mass, which states that in a chemical reaction, the mass of the reactants must equal the mass of the products. For this purpose, we calculate mole-to-mole ratios between reactants and products, and a balanced equation helps us determine the correct amounts of reactants and products needed for that specific reaction.

Now, let's go through each of the remaining choices and explain why they are not the best choices: a. The chemicals will not react until you have added the correct mole ratios. This statement is somewhat misleading because while the correct mole ratios are vital for optimal product formation, chemical reactions can still occur even without perfect mole ratios. b. The correct products will not be formed unless the right amount of reactants have been added. This choice is incorrect because the right products will form even if the amounts of reactants aren't perfect. However, the yield of the products may not be as high as when the correct reactant amounts are used. c. A certain number of products cannot be formed without a certain number of reactants. This statement is also somewhat misleading because products can be formed even if the correct number of reactants is not present. The excess reactant may limit the amount of product formed, but it does not entirely prevent the products from forming. e. A mole-to-mole ratio must be established for the reaction to occur as written. This statement is not accurate because the reaction will still occur even if the mole-to-mole ratio is not established. The mole-to-mole ratio helps to find the optimal amounts of reactants and products for a given reaction, but it does not dictate whether the reaction will occur or not.