CH3CH2COOH(aq) + H2O(l) ---> CH3CH2COO−(aq) + H3O+(aq)
The key to idenitifying Bronsted-Lowry acid-base pair and realizing that acid and base must differ in only one Hydrogen. According to the theory, Bronsted-Lowry acid is a proton (H+) donor, and Bronsted-Lowry base is a proton (H+) acceptor. When looking at the equation we must first look at reactants and then at products. In the equation given above, we see that CH3CH2COOH(aq) on the reactant side turned into CH3CH2COO−(aq) on the product side, therefore looking an H+. Thus, we conclude that CH3CH2COOH(aq) is the acid and CH3CH2COO−(aq) is its conjugate base. We can also spot another conjugate pair. H2O is turned into H3O+ on the product side. Therefore H2O is the base and H3O+ is its conjugate acid.
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