Question

Identify the acid, conjugate acid, base, and conjugate base in the following equation using the Bronsted-Lowry Theory. Label your answers to correspond with each part as shown in the equation(A) NH3(aq) + (B) HOH(l) left right arrow (C) NH4+(aq) +(D) OH–(aq)

Answer 1

NH₃ is a base

HOH the acid

NH₄+the conjugate acid

OH the conjugate base

Procedure

Upon inspection of the equation, we see that NH₃ has turned into NH₄+, which means that it gained a proton (a hydrogen ion), while HOH (water) has turned into OH, and so has lost a proton.

Using the Bronsted-Lowry acid-base theory, acids donate protons and bases accept protons.

So here, NH₃ is a base, as it accepted a proton to form NH₄+, and that makes HOH the acid, as it donated a proton and turned the reactant into OH.

In the Bronsted-Lowry acid-base theory a conjugate acid is a base that has accepted a proton, while a conjugate base is an acid that has lost a proton.

Since NH₄+ is formed after the base, NH₃, has gained a proton, then that makes NH₄+the conjugate acid. Meanwhile, OH is the result of HOH, the acid, donating its proton, thus making OH the conjugate base.