Top 10 viva/interview questions on alkalinity test of water sample

The principal objection of alkaline water is the reactions that can occur between alkalinity and certain cations in waters. The resultant precipitate may corrode pipes of water conveying systems. Alkalinity is capacity of water primarily a way of measuring the acid neutralizing. In other words, acid neutralizing is an ability of water to maintain a relatively constant pH. The possibility to maintain constant pH is due to the hydroxyl, carbonate and bicarbonate ions present in water.

Alkalinity of water

The ability of natural water to act as a buffer is controlled in part by the amount of calcium and carbonate ions in solution.
Carbonate ion and calcium ion both come from calcium carbonate or limestone.
Large amount of alkalinity causes bitter taste in water.

So water that comes in contact with limestone will contain high levels of both Ca++ and CO3-- ions and have elevated hardness and alkalinity.

Here are some viva questions-answers based on the test for alkalinity of water sample.

1. Alkalinity of water is an indication of

a) Base neutralizing capacity
b) Acid neutralizing capacity
c) Quantity of base present
d) Quality of base present

2. Mixed indicator is a combination of

a) Bromcresol Blue and Methyl Orange
b) Bromcresol Green and Methyl Red
c) Bromcresol Blue and Methyl Red
d) Bromcresol Green and Methyl Orange

3. Alkalinity is present due to all except _____.

a) Bromates
b) Phosphates
c) Silicates
d) Chlorides

4. Alkalinity is not caused by

a) Carbonates ions
b) Bicarbonates ions
c) Hydroxyl ions
d) Chloride ions

5. The phenolphthalein alkalinity is present then the pH of that water will be More than

a) 8.3
b) 9.3
c) 7.3
d) 6.3

6. Alkalinity of natural water is mainly due to the presence of _______.

a) Bicarbonates
b) Bromates
c) Phosphates
d) Silicates

7. The bicarbonate equivalence point normally occur at pH

a) 2.5
b) 3.5
c) 4.5
d) 5.5

8. What is ppm?

a) Parts per meter square
b) Parts per meter
c) Parts per million
d) Parts per millimeter

9. The normality of the acid used in the titration is ___.

a) 0.2 N
b) 0.02 N
c) 0.002 N
d) 2.0 N

10. A standard solution is a

a) Solution of accurately known strength
b) Solution of accurately known pH
c) Coloured solution
d) Colourless solution

ANSWER KEY:
1) b
2) b
3) d
4) d
5) a
6) a
7) c
8) c
9) b
10) a

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