How does pressure affect pH

Institute Dr. Flad
Vocational college for chemistry, pharmacy, biotechnology and the environment

PH value

The pH value is also very important for assessing the water. The range of possible pH values ​​ranges from pH 0 (extremely acidic, e.g. hydrochloric acid) to pH 14 (extremely basic, e.g. sodium hydroxide solution). These extreme values ​​are not reached in normally contaminated water, however, in the middle of the pH scale is the so-called neutral point with a pH value of 7, ideally the pH value of clean water should be close to pH 7, but there are minor deviations common and harmless to health.

Among other things, water has the ability to absorb and dissolve carbon dioxide from the air. This creates carbonic acid in the water, which can lower the pH value to approx. PH 5.5-6 (= acidification of the water). Acid water in the sense described above is therefore present in every mineral water that has been mixed with carbon dioxide. Too low a pH value in drinking water (e.g. pH 4-5) can lead to increased corrosion in metallic drinking water pipes. The drinking water can then be contaminated by the slowly dissolving metal. A shift of the pH value into the basic range (pH greater than 7) gives, among other things. Indications of excessive plant growth in the ecosystem (consumption of carbon dioxide by the plants) or the presence of impurities, e.g. B. by washing liquors. The pH value can also be greater than 7 due to high lime content.

Fish are very sensitive to fluctuations in the pH value. The optimal pH range for some fish species is e.g. T. very tight and is z. B. for trout between pH 4 and pH 9. Ornamental fish can prefer a significantly smaller optimal pH range. Regular monitoring of the pH value is therefore a matter of course for aquarium owners and fish farmers.



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