Complete the following sentences 1. a salt consisting of the conjugate base of a and conjugate acid of a will be neutral since neither will react with water. 2. the salt consisting of the conjugate base of a and the conjugate acid of a will be acidic since the conjugate of a is acidic. 3. a salt consisting of the conjugate base of a and the conjugate acid of a will be basic since the conjugate of a is basic. 4. a salt consisting of the conjugate base of a and conjugate acid of a can be either acidic or basic depending on the relative ka and kb of the respective ions.

answer:

let’s go to a chemistry lab and conduct a simple experiment. as shown below, we have

two solutions - 50 ml of a and 50 ml of b respectively

a solution of 0.2m hydrochloric acid (hcl)

a solution of 0.2m sodium hydroxide (naoh)

ph meter to measure ph of the solution

illustration of experiment 1 and experiment 2

illustration of experiment 1 and experiment 2

experiment 1: the ph of solution a is 7.0 i.e. it’s neutral. when we add 10 ml of 0.2m hcl to it, the ph decreases to 1.5. on the other hand, when we add 10 ml of 0.2m naoh to solution a the ph shoots up to 12.5. in both these cases we see a drastic change in ph due to either the increase or decrease of proton [h^\text{+}  

+

start superscript, start text, plus, end text, end superscript] concentration. remember, ph of a solution is dependent on the concentration of hydronium ions or simply put as [h^\text{+}  

+

start superscript, start text, plus, end text, end superscript].

experiment 2: let’s see what happens when we repeat the same experiment with solution b, whose ph is also maintained at 7.0. when we add 10 ml of 0.2m hcl to it, the ph decreases by only 0.2 units to 6.8. next, when we add 10 ml of naoh to solution b, the ph just slightly rises to 7.2 from 7.0. in both these cases we do not see a drastic change in ph, as we observed with solution a.

so, our observation from this experiment is that solution a underwent drastic changes in ph upon addition of a strong acid or a strong base, while solution b resisted a change in ph.

can you guess what the difference might be between solutions a and b?

solution a is pure ‘water’, while solution b is a ‘buffer’.

explanation: