Question

EDTA. 20mL
calculate the hardness of a water sample, whose
I loome required 20 ml of
of calcium
chloride solution whose Strength is Equivalent to
1.05 g of calo3 per litre required some of EDTA
solution.​

Answer 1

Answer:

Explanation:

The standard water contains 15 g of CaCO3/l.

1000 ml of standard hard water (SHW), therefore, contain 15,000 mg of CaCO3.

1 ml of standard water = 15,000/1000 = 15 mg of CaCO3 equivalent.

25 ml of EDTA solution = 20 ml of SHW contains of CaCO3 equivalent.

1 ml of EDTA solution = 300/25 = 12 mg of CaCO3 equivalent.

Calculation of hardness of water:

100 ml of water 18 ml of EDTA solution

mg of CaCO3 equivalent.

1000 ml of water 2160 mg of CaCO3 equivalent.

Hence, hardness of water = 2160 mg/l or ppm.

Calculation of permanent hardness of water:

100 ml of water (after boiling) 12 ml of EDTA solution

mg of CaCO3 equivalent.

1000 ml of water 1440 mg of CaCO3 equivalent.

Hence, permanent hardness of water = 1440 ppm.

Calculation of temporary hardness of water:

Temporary hardness of water = (Total – Permanent) hardness

Thus,

Temporary hardness of water = 2160 – 1440 = 720 ppm.

Answer: Temporary hardness of water = 720 ppm.