Question

Short Answer Questions.

a) Predict the effect (increase, decrease, no change) on the alkalinity of a natural water upon addition of the following compounds. Explain your answers:
i. CO₂
ii. HNO₃
iii. CdCl₂
iv. NH₃
v. Sulphate reduction (SO4^2- H2S)

Answer 1

Answer:

Alkalinity:

It is the measure of the Basicity of the water or the solution.

(or) It is the measure of the amount of the chemical bases. (or) Measure of the P^H of the water or solution.

i) CO₂ - Decreases

Explanation:

It is acidic in nature and forms Carbonic acid in the water. Hence the Acidic nature increases and Alkanity decreases.

H₂O + CO₂ H₂CO₃

It shows the lower P^H value.

ii) HNO₃ - Decreases

Explanation:

It is the strong acid the Alkanity of the water decreases and the Acidity increases.

iii) CdCl₂ - No change

Explanation:

It is the neutral compound. Hence the Alkanity of the water can not change.

iv) NH₃ - Increases.

Explanation:

Ammonia gas dissolves in the water due to the formation of the H-bonds. It is the Basic nature and forms the Ammonia solution.

Hence the Alkanity of the water increases.

NH₃ + H₂O NH₄OH

v) Sulphate reduction (SO^2-₄  H₂S) - Decreases

Explanation:

H₂S is the gas and it is Acidic in nature. It dissolves in the water and the water becomes as a acidic solution. Hence the Alkanity of the water decreases.