The limiting reactant in esterification is usually the cheapest reactant. However, you must confirm by calculating and comparing the amount of product each reactant will produce.
Consider the esterification reaction in which 18.5 g of 1-butanol are reacted with 19.0 g of acetic acid. What is the limiting reactant?
Step 1: Write the balanced chemical equation for the reaction.
C₄H₉OH + CH₃COOH → CH₃COOC₄H₉ + H₂O
Step 2: Convert all masses into moles.
18.5 g C₄H₉OH ×
19.0 g CH₃COOH ×
Step 3: Calculate the mass of product from each reactant.
0.250 mol C₄H₉OH ×
29.0 g CH₃COOC₄H₉
From acetic acid:
0.316 mol CH₃COOH ×
36.8 g CH₃COOC₄H₉
Since 1-butanol gives the smaller amount of product, it is the limiting reactant.