what does pH mean - Simplified
What does pH mean?
value represents a fluid’s acidity or alkalinity level -
by indicating its concentration of hydrogen ions (H+) and therefore
its potential for attracting more
pH values of fluids range from 0 to 14
(very strong to very weak acids or bases/alkalis)
solution with a pH of 0 has no ability to attract hydrogen ions.
The pH scale goes from 0 to 14 and is logarithmic -
that each step is ten times higher that the previous. (E.g. pH of 4.3 is 10
times more acid than 5.3, and 100 times more acidic than 6.3)
pH = – log
(H+ conc.) On the logarithmic scale the difference between each pH
number is a factor of 10. A pH of 5
means 10-5 (i.e. 1/105
) g/L of H* ions. i.e. 10 x more acidic than a pH of 6 (10-6 g/L)
The STRENGTH of an acid or base is determined by how fast and how much of it
dissociates into ions – E.g. A strong acid will have lots of H+
ions, a weak acid not so many.
Ionization occurs when
molecules are “pulled” apart in solution, creating negative and positive ions -
E.g. Water (H2O or HOH) is
usually very weakly ionized, but certain substances can "pull" at the water to
separate it into electrically charged H+ and OH- ions
(When these ions are in equal proportions, the pH is a neutral 7). Most organic
acids are weak, but mineral acids (e.g. HCl) are much stronger.
An acid can be
neutralized by adding an alkali
Contains more H+ ions than OH- ions;
Can donate protons
electrons/negatively charged ions
Contains more OH-
ions than H+ ions
Can accept protons
electrons/negatively charged ions.
positively charged ion e.g. Hydrogen ion ( H+ );
Electrons /negatively charged ions – carry a negative charge e.g. hydroxyl ion (OH-)