Question

26. A sample of hard water is found to contain 40 mg of Ca2+ ions per litre. The amount of

washing soda ( Na2CO3) required to soften five litres of the sample would be

a) 1.06 grams b) 5.3 grams c) 53 mg d) 530 mg​

Answer 1

Answer:

Explanation:

Equivalent of ion = equivalent of solution

Here mg/lt tells amount of caco3 in 1000 lt solution

40 gm in 1000 lt water sample

Equivalent of ca+2 =moles*f

=2

Equivalent of caco3 = 2

Moles*f = 2

Moles×2=2

Moles=1

Mass of caco3 = 100 gm

Equivalent of caco3 = equivalent of na2co3

Moles1=moles2

Mass of na2co3= 106

106 gm for 1000 lt

106/200 gm for 5 lt

53 mg