Where are acids bases and neutral substances located on the pH scale?
The pH scale exists from 0 to 14.The less the pH, more is the
solution acidic and more the pH the more it is basic. 7 indicates
neutral.
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The pH scale measures hydrogen ion (H+) concentration in a
substance. For example, water (H2O) has a neutral pH of 7. Some of
the water molecules will naturally dissociate (or break apart),
forming hydrogen ions (H+) and hydroxyl ions (OH-). So you have
positive and negative charges. In water, there are approximately
the same number of H+ and OH- ions (as well as neutral H2O
molecules and, as such, the pH is said to be neutral.
Acids donate H+ (or increase the H+ concentration), which means
there are more H+ ions floating free in the mixture and the overall
charge of the substance is positive (due to all those extra
positive ions floating about). A pH of less than 7 is acidic.
Bases (or alkaline substances) accept H+ ions, meaning there is
a lower concentration of H+ and the solution has an overall
negative charge. A pH of more than 7 is basic.
You can apply the pH scale to solutions to determine its acidic
or basic nature (or how well it frees up or binds to H+ ions).
Because the pH scale is logarithmic, a small change in pH means a
big change in concentration. For example, a pH of 7 equals a H+
concentraion (relative to water) of 1. A pH of 6 is equal to a H+
concentration of 10, pH 5 is equal to H+ concentration of 100 and
so on.
