Question

Which of the following are conjugate acid/base pairs? Select all that apply.

Answer 1

Answer: $HCOOH$ and $HCOO^-$

$HNO_3$ and $NO_3-^-$

$H_2SO_4$ and $SO_4^{2-}$

$H_2CO_3$ and $CO_3^{2-}$

Explanation:

According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.

For the given chemical equations:

1. $HCOOH(aq)\rightarrow HCOO^-(aq.)+H^+(aq.)$

Here, $HCOOH$ is loosing a proton, thus it is considered as an acid and after losing a proton, it forms $HCOO^-$ which is a conjugate base.

2. $HNO_3(aq)\rightarrow NO_3^-(aq.)+H^+(aq.)$

Here, $HNO_3$ is loosing a proton, thus it is considered as an acid and after losing a proton, it forms $NO_3^-$ which is a conjugate base.

3. $H_2SO_4(aq)\rightarrow SO_4^{2-}(aq.)+2H^+(aq.)$

Here, $H_2SO_4$ is loosing a proton, thus it is considered as an acid and after losing a proton, it forms $SO_4^{2-}$ which is a conjugate base.

4. $NaCl$ and $NaOh$ are not conjugate acid/ base pairs.

5. $H_2CO_3(aq)\rightarrow CO_3^{2-}(aq.)+2H^+(aq.)$

Here, $H_2CO_3$ is loosing a proton, thus it is considered as an acid and after losing a proton, it forms $CO_3^{2-}$ which is a conjugate base.