Question

Problems:
1. 250 mL of a water sample on EDTA titration with Eriochrome Black -T consumed 13 mL of
0.022 N EDTA till end point is reached, Calculate the hardness of water ?​

Answer 1

Hardness of water is 114.4 ppm

Explanation:

1 ml of 0.01 M EDTA = 1mg of CaCo3 equivalents

13 ml of 0.022 M EDTA = 1 ×13×0.022/1×0.01

= 28.6 mg of Caco3

This amount of hardness is present in 250 ml water sample.

hardness present in 1 litre = 28.6/250×114.4 ppm

Answer 2

Answer:

Amount of Hardness present in 1 liter of water sample is 114.53 ppm

Explanation:

Hardness of Water Definition : Soap destroying properties of water due to the presence of Calcium and Magnesium ions.

1 ml of 0.01M EDTA = 1 mg CaCO₃ with Mg

similarly,

$\ 13 \ ml \of\ 0.022 M\ EDTA = \ \frac{1 \times 13 \times 0.022}{1 \times 0.01}$

Amount of Hardness present in 250 ml of water sample = 28.6 mg of CaCO₃

Amount of Hardness present in 1 liter of water sample,

$\frac{28.6\times 1000} {250} = 114.4\ mg \ of\ CaCO _3$

114.4 mg/l = 114.53 ppm

Therefore, Amount of Hardness present in 1 liter of water sample is 114.53 ppm