Stoichiometry Module: Limiting Reactants
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If 200 g salicylic acid is added to 100 g acetic anhydride, which reactant will limit the reaction?

In Step 2, you had to choose a reactant (the calculation was done using salicylic acid). To show that the choice of reactants is arbitrary, let's see what would have happened if acetic anhydride was choosen.

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How many moles of salicylic acid will react with the 0.980 moles of acetic anhydride present?

0.490 moles 0.980 moles 1.96 moles

Good!

The amount of salicylic acid present (1.45 moles) is not enough to react completely with all of the acetic anhydride. Thus, the salicylic acid will limit the reaction.

Remember that every mole of salicylic acid will react with two moles of acetic anhydride (from the balanced chemical equation).