Question

Which of the following solutions is a good buffer system? O A) a solution that is 0.10 M HC2H302 and 0.10 M LIC2H302 O B) a solution that is 0.10 M HF and 0.10 M NaC2H302 O c) a solution that is 0.10 M HCl and 0.10 M NH4+ OD) a solution that is 0.10 M NaOH and 0.10 M KOH

Answer 1

Answer : The correct option is, (A) a solution that is 0.10 M $HC_2H_3O_2$ and 0.10 M $LiC_2H_3O_2$

Explanation :

Buffer : It is defined as a solution that maintain the pH of the solution by adding the small amount of acid or a base.

As we know that there are two types of buffer which are acidic buffer and basic buffer.

Acidic buffer : It is defined as the solution that have the pH less than 7 and it contains weak acid and its salt or conjugate base. For example : Acetic acid (weak acid) and sodium acetate (salt or conjugate base).

Basic buffer : It is defined as the solution that have the pH more than 7 and it contains weak base and its salt or conjugate acid. For example : Ammonia (weak base) and ammonium chloride (salt or conjugate acid).

(A) a solution that is 0.10 M $HC_2H_3O_2$ and 0.10 M $LiC_2H_3O_2$

It is a mixture of weak acid $(HC_2H_3O_2)$ and its conjugate base (salt) $(LiC_2H_3O_2)$. So, it is a good buffer.

(B) a solution that is 0.10 M HF and 0.10 M $NaC_2H_3O_2$

It is not a buffer system because $NaC_2H_3O_2$ is not a salt of weak acid HF.

(C) a solution that is 0.10 M HCl and 0.10 M $NH_4^+$

It is not a buffer because HCl is a strong acid.

(D) a solution that is 0.10 M NaOH and 0.10 M KOH

It is not a buffer because NaOH and KOH are a strong base.

Hence, the correct option is, (A)