Question

For a sample of water with the ionic composition shown below, the Carbonate and Non-carbonate hardness concentration (in mg/l as $CaC{O}_3$) respectively are.

• A. 200 and 50
• B. 50 and 200
• C. 75 and 175
• D. 175 and 75

Answer 1

The correct option is D 175 and 75

$Carbonatehardness=3.5\times {10}^{-3}g-eq$

[if NCH is present sodium alkalinity will be absent i.e., $NaHC{O}_3$ absent]

$=3.5\times {10}^{-3}\times \frac{50g}{l}asCaC{O}_3$
$=175mg/LasCaC{O}_3$

Non carbonate hardness $=$ Total hardness - Carbonate hardness

Total hardness
$=5\times 50mg/LasCaC{O}_3$
$[totalhardnessisduetoC{a}^{2+}andM{g}^{2+}$]

$=250mg/LasCaC{O}_3$

$\Rightarrow NCH=250-175=75mg/LasCaC{O}_3$