The Islamic University of Gaza Faculty of Engineering Civil Engineering Department Environmental Engineering (ECIV 4324) Chapter 2 – Chemical Water Quality. Water Quality: Definition, Characteristics, and Perspectives. Contents. Chemical water – quality parameters.
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The Islamic University of GazaFaculty of EngineeringCivil Engineering DepartmentEnvironmental Engineering(ECIV 4324)Chapter 2 – Chemical Water Quality
Water Quality: Definition, Characteristics, and Perspectives
For example :
one mole of oxygen (O2) = 32, water (H2O) =18
The valence of (Na+)=1,
The valence of (Cl-)=1
How many grams of calcium will be required to combine with 90 g of carbonate to form calcium carbonate?
1- One equivalent of Carbonate (CO32-)
2- One equivalent of Calcium(Ca2+)
3- The no. of equivalents of Carbonate must equal to the no. of equivalents of calcium.
5- So, we need 3 equiv of carbonate = 3 equiv X 20 g/equiv = 60 g.
What is the equivalent calcium carbonate concentration of:
1- One equivalent of Calcium Carbonate (CaCO3)
2- One equivalent of Sodium Chloride (NaCl)
One mole of a substance divided by its valence is one equivalent
K is an equilibrium constantfor a given substance in pure water at given temperature
The brackets [ ] indicate molar concentration.
Where Ksp is the solubility product.
If the concentration of either or both of the ions is increased , the product of the ionic concentration will exceed the Ksp and precipitation will occur to maintain the equilibrium conditions.
See table 2-3 (solubility product values)
The solubility product for the dissociation of Mg(OH)2 is 9x10-12. Determine the concentration of Mg2+ and OH- at equilibrium, expressed as milligrams per liter CaCo3.