Question

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 will make.
e. A mole-to-mole ratio must be established for the reaction to occur as written.

What is the best choice? For those you did not choose, explain why they are incorrect. State the fundamental reason why an equation for a reaction must be balanced.

Short answer

The balanced equation tells you how much reactant you need and allows you to predict how much product you will make. Option (d) is the best choice.

Step-by-step solution

Chemical equation

A chemical change can be best described in a short form notation bychemical equation. The chemical equation consists of reactants on the left side and the products on the right side.

If it is a balanced chemical equation, then the number of atoms of each species remains the same and it follows the law of conservation of mass. It also helps in predicting the yield.

Explanation

Option (a): The statement is false due to the reactivity of molecules in the correct mole ratio. Correct mole ratio will be used for the determination of the formation of product moles.

Option (b): This statement is false due to the consequence of product identity, not quantity.

Option (c): This is actually not a perfect reason due to their balancing of chemical equations. It can always add a reactant number without chemical equation balance.

Option (e): This statement is false. The reaction of molecules can react with the correct mole to mole ratio.

Best choice

Option (d): This is the best choice because of the need in equation balancing to get the fact what amount of reactant is needed and helps to find the product amount. This is true.