What is the normal pH value?

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ncchemist | eNotes Employee

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pH is the measure of the concentration of protons in a solution (usually water).  It is mathematically defined as:

pH = -log[H+]

This means that the pH of a solution is the negative log of the concentration of protons in moles per liter.  pH is in essence a measure of the acidity or basicity of a solution.  It is based on a standard scale of 0 to 14 with 0 being the most acidic and 14 being the least acidic (most basic).  Since it is a logarithmic scale, a difference of one pH unit is really an order of magnitude difference.

There is no truly "normal" pH value.  A pH of 7 is a completely neutral solution (equal concentrations of H+ and OH-).  It is neither acidic nor basic.  Normal drinking water is usually slightly acidic in nature (around pH 6).  So I suppose the answer you are looking for is either 7 or slightly below that.

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