What is pH?

  • (noun): (chemistry) p(otential of) H(ydrogen); the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is acidic and less than 7 is basic).
    Synonyms: pH scale


In chemistry, pH is a measure of the activity of the (solvated) hydrogen ion. p, which measures the hydrogen ion concentration is closely related to, and is often written as, pH. Pure water has a pH very close to 7 at 25°C. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. Measurement of pH for aqueous solutions can be done with a glass electrode and a pH meter, or using indicators.

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Some articles on pH:

Human Parainfluenza Viruses - Interactions With The Environment
... which are important for hPIV survival are pH, humidity, temperature and the medium the virus in found within ... The optimal pH is around the physiologic pH values (7.4 to 8.0), whilst at high temperatures (above 37°C) and low humidity, infectivity reduces ...
Chiayi County - Administration
... Hakka Pha̍k-fa-sṳ City Puzi City 朴子市 P'u-tzu Puzih Phò-chú Phú-chṳ́ Taibao City 太保市 T'ai-pao Taibao Thài-pó Thai-pó Urban townships Budai Township 布袋鎮 Pu-tai Budai Pò͘-t ...
Calculations of PH - General Method
... general formulae such as ApBqHr the following general method can be used to calculate the pH of a solution ...
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... Crude 50 ... Angola Block 15 Kizomba Ph 1 (Clochas Mavacola) 2012 ExxonMobil ODW Crude 2000 ... Angola Block 14 Negage 2012 Chevron ODW Crude 75 2002 ... Mexico Ayin-Alux 2012 Pemex OFF 0.173 70 ... Russia Verkhnechonsk Ph 2012 ... TNK-BP Rosneft LAND Crude 1.480 1978 ... UK Cheviot 2012 Chevron OFF Crude 20 USA Caesar Tonga 2012 Anadarko ODW Crude 0.2 50 No ...
... Nitrobacter have an optimum pH between 7.3 and 7.5, and will die in temperatures exceeding 120°F (49°C) or below 32°F (0°C) ... seem to grow optimally at 38°C and at a pH of 7.9, but Holt states that Nitrobacter grow optimally at 28°C and grows within a pH range of 5.8 -8.5 and has an pH optima between 7.6 and 7.8 ...