Question

For the given reaction:
$C{H_3}COOH + {C_2}{H_5}OH \to C{H_3}COO{C_2}{H_5} + {H_2}O$
When $72{\text{g}}$ of acetic acid is made to react with $46{\text{g}}$ of ethanol?
A.Acetic acid will be the limiting reagent
B.Alcohol will be the limiting reagent
C.Alcohol will be the excess reagent
D.Acetic acid will be the excess reagent

Answer 1

To solve this question, you must recall basic stoichiometric fundamentals. In every reaction, the reactant which is present in a lesser amount and limits the chemical reaction is known as limiting reagent while the other reactant that is left after the limiting reagent is exhausted is known as the excess reagent.

Complete step by step answer:
For the reaction given in the question, $C{H_3}COOH + {C_2}{H_5}OH \to C{H_3}COO{C_2}{H_5} + {H_2}O$
We can conclude that one mole each of both the reactants react to form one mole of product. Since in the given reaction, both the reactants react in equal amounts, thus, we can say that the reactant present in a lesser amount will be the limiting reagent.
We know that the molar mass of acetic acid is $60{\text{g}}$ and that of ethanol is $46{\text{g}}$
The number of moles of acetic acid given in the question are ${n_{aa}} = \dfrac{{72}}{{60}} = 1.2$ .
The number of moles of ethanol given in the question are ${n_{ea}} = \dfrac{{46}}{{46}} = 1$
So, the limiting reagent is ethanol and the excess reagent is acetic acid.

Thus, the correct answers are B and D.

Note:
Stoichiometry is based upon the very basic laws of chemistry that help to understand it better, namely, the law of conservation of mass, the law of definite proportions (the law of constant composition), the law of reciprocal proportions and the law of multiple proportions . In general, different chemicals combine in definite ratios in chemical reactions. Since matter can neither be created nor destroyed, nor can one element change into the other in a chemical reaction, thus the amount of each element must be the same throughout the entire reaction. For example, the number of atoms of any element in the reactants will be always equal to the number of atoms of that element in the products formed.