| pH Level of Soils *Boy, that sounds really interesting doesn't it?* | |||||||||||||||||
| Background Information | The pH Scale | ||||||||||||||||
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The Danish scientist Soren Sorensen (1868-1939) proposed the pH scale in 1909; having ph equal to: -log[H+]. By definition, pH is the negative log of the hydronium ion (H+) concentration. The hydronium ion is simply the ion which make acids acidic. It is so reactive, because it easily bonds with other chemical to transform them into something with different properties. Likewise a basic solution is basic because of the hydroxide ion (OH-). Basically, the pH is the value used to denote the acidity, or rather, the hydrogen-ion concentration, of a solution. |
The pH scale was created as a means to gauge and record acidity or alkalinity. Since hydrogen ion activity lies mainly between 1 to 1 x 10 -14 The pH scale range from 0 to 14. Thus, the scale is divided up into 14 sub-levels, all of which denote a certain level of acidity. ~ If the pH of a substance is 7.0, or quite close, then it is neutral. ~ If it is greater than 7.0, then it is a base. ~ If it is lower than 7.0, then it is an acid. Each whole number drop in pH denotes ten times the acidity. For example, a soil having a pH of 5 is ten times more acidic than one having a pH of 6. Two good examples of acid and alkaline liquids are orange juice and seawater. Orange juice has a pH of about 3.7 (very acid) while seawater has a pH of 7.9 (slightly alkaline). | ||||||||||||||||
| Measurement Techniques | |||||||||||||||||
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The pH of a solution may be measured by means of: 1) Litmus paper - A special paper which can detect the hydrogen ion concentration of a solution; RED denotes acidity, while BLUE denotes alkalinity. Some litmus paper come with a colour scale which will allow the user to roughly determine the value of the pH being measured. 2)PH meter - This is an electronic instrument which electrochemically measures pH values and the value measured is shown digitally by an LCD screen. | |||||||||||||||||
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