Final answer:
Without the correct balanced equation for the reaction of BaCl₂ and KIO₃, we cannot predict which reagent would be in excess. If they reacted in a 1:1 mole ratio, neither reagent would be in excess given equal volumes and concentrations.
Step-by-step explanation:
To determine which reagent would be in excess after reacting 7.5 mL of a 0.10M BaCl₂ solution with 7.5 mL of a 0.10M KIO₃ solution, you first need to write and balance the chemical equation. Unfortunately, since BaCl₂ and KIO₃ do not directly react to form a simple product, and no specific reaction is given, we cannot balance the equation as is. Therefore, without a correct reaction or additional context, we cannot accurately predict which reagent would be in excess based on the information provided.
However, if we were to consider a hypothetical situation where BaCl₂ and KIO₃ react in a 1:1 mole ratio, you would calculate the number of moles of each reactant using the concentration and the volume. In this case, both solutions have the same concentration and volume which means that if they were to react in a 1:1 ratio, neither reagent would be in excess as they would be completely consumed if the reaction goes to completion.