Certification Action Line — Answers — May 2014

1. Chemistry. Knowledge of basic chemistry is useful to understanding the properties of substances in water and the transformations they undergo in effective water treatment.
2. False. The term "element" is applied to substances that cannot be decomposed chemically into a simpler substance. Each element contains only one kind of atom. The matter of the universe is composed of 92 naturally occurring elements ranging from hydrogen, the lightest, to uranium, the heaviest. In addition to the naturally occurring elements, about 17 elements heavier than uranium have been made by bombarding elements with subatomic particles in devices known as particle accelerators. A compound is formed by the chemical combination of two or more elements.
3. Ion. Atoms and molecules become electrically charged and form ions by gaining or losing electrons. The amount of electric charge an ion has is determined by the number of electrons gained or lost by the atom or molecule and is equal to the valence of that element or compound. Negatively charged ions are called anions; positively charged ions are called cations.
4. Conductivity. The concentration of freely moving ions in a solution is indicated by the solution’s ability to conduct electricity, and is a measure of the TDS of the solution. For example, pure water is a poor conductor of electricity. But, water containing enough ions is a good conductor.
5. Equivalent weight. The equivalent or combining weight of an element, ion or compound is its atomic or formula weight divided by its valance.
6. 50.045. Calcium carbonate (CaCO₃ ) has a molecular or formula weight of 100.089 (Ca=40.08, C = 12.011, O₃ = 3 X 15.9994 = 47.993) and its highest positively charged atom (Ca⁺² ) has a valence of 2, so the equivalent weight is 100.089 ÷ 2 = 50.045.
7. 5,994 grains. The equivalent weight of NaCl is 58.443 (Na⁺ = 22.99, Cl^– = 35.453, highest valence is +1). One pound equals 7,000 grains. Calcium carbonate equivalent is calculated by multiplying the weight of the material by the ratio of the equivalent weight of CaCO₃ over the equivalent weight of the materials. Therefore, one pound of NaCl equals: 1 pound X 7,000 grains/pound X 50.045/58.443 = 5994 grains when measured as CaCO₃.
8. 50, liter. Normality is often used to determine the concentration of a solution used in the laboratory. Normality is defined as the gram equivalent weight of solute per liter of solution.
9. Oxidation-reduction. Soluble ferrous iron, manganous manganese and hydrogen sulfide are oxidized to insoluble and filterable ferric iron, manganic manganese and elemental sulfur while the manganese in potassium permangante is reduced from +7 valance to the manganic +4 valence.
10. 8.34. One milligram per liter equals one part per million or one pound in a million pounds of water. A gallon of water weighs 8.34 pounds.

              Therefore,     1 lb.  ­­          X 8.34 lbs./gallon = 8.34 lbs/1,000,000 gallons.               

                                1,000,000 lbs.