Conductivity
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Digital conductivity meter
(Source www.amberscience.com) |
Cinductivity is the ability of water to carry an electric current. It can be measured using a conductivity meter. Pure water is not a good conductor of electricity. Ordinary distilled water in equilibrium with carbon dioxide of the air has a conductivity of about 0.5µScm−1 to 2.0µScm−1. Because the electrical current is transported by the ions in solution, the conductivity increases as the concentration of ions increases. Thus conductivity increases as water dissolved ionic species.
Typical conductivity of waters:
Distilled water:0.5 µ S cm−1 to 2.0 µ S cm−1
After usage: 2.0 µ S cm−1 to 4.0 µ S cm−1
Normal portable water :50 µ S cm−1 to 1500 µ S cm−1
Industrial waste: > 10000 µ Scm−1
Water pH
pH is a measurement of how acidic or how basic (alkaline) a solution is. pH is measured on a scale of 0 to 14. Water that is neutral has a pH of 7. Acidic water has pH values less than 7, with 0 being the most acidic. Likewise, basic water has values greater than 7, with 14 being the most basic. A change of 1 unit on a pH scale represents a 10 fold change in the pH, so that water with pH of 6 is 10 times more acidic than water with a pH of 7, and water with a pH of 5 is 100 times more acidic than water with a pH of 7.
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| Figure : the pH of some solutions |
In most industries such as food preservation, beverages, process control. production of chemicals and production of fertilizers, agrochemicals, water pH is a most important factor.
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Digital pH meter
(Source:www.saskschools.ca) |
pH meter is used to measure pH of a liquid. pH electrode has a glass membrane at the tip. This glass membrane allows to transfer H+ ions. Normally we're measuring the activity of H+ ions, while assuming the solutions are diluted. First we have to calibrate the pH meter using pH=7 and pH=7 or pH=10 buffer solutions. Calibration is the step where check the instrument functions according to the known theoretical relationship. Daily calibrations are recommended for pH meters. Also potential measurements are always depend on temperature. Therefore, it is better to control temperature in potential measurements.
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