Question

Which of the following is the conjugate acid of H₂S?

Select one:

a. H3S+

b. H+

c. H2SO4

d. HS-

e. S

Which of the following is a weak acid?

Select one:

a. salicylic acid

b. hydrochloric acid

c. sulfuric acid

d. hydrobromic acid

e. nitric acid

Which of the following is the conjugate base of H₂S?

Select one:

a. SO2

b. S

c. OH-

d. SH-

e. H3S+

If the [H+] = 1.0 x 10^-9, what is the pH?

Select one:

a. 1.0 x 10-5

b. 1.0 x 10-9

c. 5

d. 1.0 x 10-14

e. 9

If the [H+] = 1.0 x 10^-9, what is the [OH-]?

Select one:

a. 1.0 x 10-14

b. 1.0 x 10-5

c. 5

d. 9

e. 1.0 x 10-9

Answer 1

1. In the Bronsted–Lowry acid–base theory,the conjugate acid is a chemical compound formed after accepting of a proton (H+) by a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a hydrogen ion.

i.e. Acid + Base ⇌ Conjugate Base + Conjugate Acid

Hence, the conjugate acid of H2S is H3S+.Hence, option a is correct.

2.The mineral acids are generally strong acids because they ionize in water completely. Hence here, Salicylic acids is weak acid than hydrochloric acid, Sulfuric acid, hydrobromic acid, nitic acid. Hence, option a is correct.

3. A conjugate base is what is left over after an acid after donating a proton during a chemical reaction. Hence, a conjugate base is a species formed by the removal of a proton from an acid, as in the reverse reaction it is able to gain a hydrogen ion.

i.e. Acid + Base ⇌ Conjugate Base + Conjugate Acid

Hence, conjugate base of H2S is HS-. Hence, option d is correct.

4.Given, concentration of [H+] =

We know

Hence, pH of the solution is 9. Option e is correct.

But in water solution the H+ of water will be counted.

Hence , concentration of H+ in the water solution will be

[H+]= +   =

pH of the solution will be   

5. If the

Then, pH of the solution = 9

We know pH + pOH = 14

Hence pOH of the solution is = 14 - 9 = 5. Option c is correct.

But in water solution the pOH of the solution is = 14 - 6.996 = 7.004