The formula to calculate the excess reagent (ER) is:
\[ ER = TR - LR \]
Where:
An excess reagent, in chemistry, refers to the reactant that is in surplus quantity during a chemical reaction. It is the substance that completely reacts with the limiting reagent (the reactant that is completely consumed in the reaction) and still remains unreacted because there is more of it than necessary for the reaction to go to completion. The excess reagent is left over after the limiting reagent is completely used up in the reaction.
Let's assume the following values:
Step 1: Calculate the excess reagent:
\[ ER = 100 - 60 = 40 \text{ units} \]
Therefore, the excess reagent is 40 units.