Question

what would cause the percent yield of a reaction to be less than 100% the product participates in a side reaction. pure reactants are used. a balanced chemical equation is used. all of the limiting reagent gets used up.

Explanation:

• Analyze each option:
• "The product participates in a side reaction": If the product reacts further (side reaction), the amount of desired product collected decreases, so percent yield (actual yield/theoretical yield ×100%) will be less than 100% as actual yield drops.
• "Pure reactants are used": Using pure reactants should maximize product formation, not decrease yield.
• "A balanced chemical equation is used": A balanced equation is for stoichiometric calculations, not a factor affecting actual yield (so not a cause for low percent yield).
• "All of the limiting reagent gets used up": If limiting reagent is fully consumed, actual yield approaches theoretical yield (percent yield could be 100% or less due to other factors, but this alone doesn't cause it to be less than 100%).

Answer:

The product participates in a side reaction.