Question

1. The following table lists the ion composition of water. What are the mg/L concentrations of each? Does this water have charge balance? If no, then some ion is missing. Would it be a cation or an anion? From these values compute the TDS in mg/L and the hardness in mg/L as CaCO3. Are these values low, normal, or high? Is any other ion out of the desired range?

Ion              Concentration, mmole/L

Ca²⁺                                     4.8

Mg²⁺                       1.2

Fe³⁺                         0.5

Na⁺                         1.5

SO₄^2-                       1.0

Cl^-                           5.0

HCO₃^-                      8.0

Answer 1

mmole*Molecular weight of ion(in g)=mg of ion

Ion              Concentration, mmole/L concentration,mg/l

Ca2+ 4.8 192

Mg2+                       1.2 28.8

Fe3+                         0.5 28

Na+                         1.5 34.5

SO42-                       1.0 96

Cl-                           5.0 177.5

HCO3-                      8.0 488

No there is no charge balance involved because electrons liberated by forming cations are not equal to electrons taken up to become anions

number of cations are more so anions are missing for charge neutrality

TDS means total dissolved solids which has come from cations

TDS=(192+28.8+28+34.5)=283.3 mg/L

and hardness is due to Mg2+ and Ca2+=(192+28.2)=220.2 mg/L

These values are little high as it makes water more hard