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What is the difference between an acidic, basic and neutral pH?

A solution having a low pH is said to be acidic, what this means is that it has a higher concentration of hydrogen ions than a neutral solution.  For example, stomach acid has a pH of around 2.0, this is equal to a concentration of hydrogen ions equal to 1 x 10-2 mol/L.  Any solution having a pH  less than 7.0 is said to be acidic.

A basic solution, such as a household cleaner usually has a pH of around 11.  This translates to a concentration of hydrogen ions equal to 1 x 10-11 mol/L.  This would be considered a lower concentration of hydrogen ions.  Recall from scientific notation that as the exponent becomes a larger negative number, the numerical value of the expression is less.  Any solution having a pH  greater than 7.0 is said to be basic. 

A pH of 7.0 means that a solution is neutral, having a medium concentration of hydrogen ions.  Solutions such as distilled water have a neutral pH and thus a concentration of 1 x 10-7 mol/L of hydrogen ions in solution.  Neutral solutions have pH values of 7.0 (or very close to 7.0).

Click here to explore how the concentration of Hydrogen ions (pH) in water will affect the organisms living in that environment.

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