BEHS Chemistry

The pH Scale


The acidic, basic, or neutral character of a solution can be measured and reported using the pH scale.

PH is short-hand for the CONCENTRATION of the hydrogen ion.

PH values commonly range from 1 to 14 although some very basic or acidic solutions may be outside this range.

A pH of 7 is a neutral solution.

PH values LOWER than 7 indicate acids; the lower the pH the more acidic the solution.

PH values GREATER than 7 indicate bases; the higher the pH the more basic the solution.

Most acid and base solutions occur in water, therefore we must consider the EQUILIBRIUM.

HOH --> H+ + OH-


As a solution becomes more acidic ( INCREASE in [H +]) the [ OH -] must decrease.

As a solution becomes more basic ( DECREASE in [H +]) the [ OH -] must increase.

Fill the following table in your lab book.


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