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The pH range is commonly given as zero to 14, but a pH value can be less than 0 for very concentrated strong acids or greater than 14 for very concentrated strong bases. [2] The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. [3]
The pH of human faeces is variable but the average is pH 6.6 for normal faeces. [1] [2] A lower faecal pH (very acidic stool) can indicate a digestive problem such poor absorption of carbohydrates or fats, [3] lactose intolerance, [4] an infection such as E. coli or rotavirus, or overgrowth of acid-producing bacteria (such as lactic acid bacteria).
Physiologically normal intracellular pH is most commonly between 7.0 and 7.4, though there is variability between tissues (e.g., mammalian skeletal muscle tends to have a pH i of 6.8–7.1). [4] [5] There is also pH variation across different organelles, which can span from around 4.5 to 8.0. [6] [7] pH i can be measured in a number of ...
An ideal pH value of 4.7 has been identified, with some individuals showing levels as low as 4.3. Subjects with a skin pH below 5.0 exhibited significantly less scaling, higher hydration levels, and better skin flora presence compared to those with higher pH levels, suggesting better overall skin condition. [6]
In and of themselves, pH indicators are usually weak acids or weak bases. The general reaction scheme of acidic pH indicators in aqueous solutions can be formulated as: HInd (aq) + H 2 O (l) ⇌ H 3 O + (aq) + Ind − (aq) where, "HInd" is the acidic form and "Ind −" is the conjugate base of the indicator. Vice versa for basic pH indicators ...
Good's buffers (also Good buffers) are twenty buffering agents for biochemical and biological research selected and described by Norman Good and colleagues during 1966–1980. [ 1 ] [ 2 ] [ 3 ] Most of the buffers were new zwitterionic compounds prepared and tested by Good and coworkers for the first time, though some ( MES , ADA , BES , Bicine ...
Soils with pH values that are higher than 7.3 are usually defined as being alkaline. These soils can occur naturally due to the presence of alkali salts. Although many plants do prefer slightly basic soil (including vegetables like cabbage and fodder like buffalo grass ), most plants prefer mildly acidic soil (with pHs between 6.0 and 6.8), and ...
The optimum pH for human catalase is approximately 7, [8] and has a fairly broad maximum: the rate of reaction does not change appreciably between pH 6.8 and 7.5. [9] The pH optimum for other catalases varies between 4 and 11 depending on the species. [10] The optimum temperature also varies by species. [11]