pH acids and bases
Introduction
The pH of a substance gives an indication of its acidity or basicity, or whether it is neutral.
If solution is strong acid= high acidity, low pH value Higher basicity or alkalinity= high pH
What is pH
pH= power of hydrogen
refers to hydrogen ions in a solution
pH of a solution is a measure of the amount
of acidity or the level of basicity of a substance when it is dissolved in a liquid.
pH requires the presence of a liquid.
pH is by definition the concentration of Hydrogen ions in a solution.
The pH scale
pH of a substance expressed as a value on a scale from 0 to 14, with neutral substance having pH of 7
Bases= +7
Acids= -7
Importance of pH
Correct levels of pH are needed for
optimum functionality in nature. example is the muscles of the human body that are made up of proteins and other substances normally function best at a pH of 6, in other words they need a slightly acidic environment. if pH of environment changes the proteins will denature.
Understanding pH
concept of pH is explained by referring to the water
molecule and the number of Hydronium ions or Hydroxide ions in a volume of water. 
Significance of H3O+
for pH
The Hydronium ions can be thought of as carriers of H+, a positively charged Hydrogen atom, it is the umber of H3O+ in a solution and therefore the number of H+ ions in a solution determines the pH of the solution.
If a substance
dissolves in water and causes the formation of a large number of H3O+ ions, the
solution will be acidic and will have a low pH value.
If a substance dissolves in water and prevents the formation of H3O+ ions, then the solution is basic and has a high pH
value.
pH therefore measures the percentage of positively charged Hydrogen ions or the strength of Hydrogen ions, present in a solution.
Three examples of solutions and their pH values
Distilled water
-negative log chances of finding a Hydrogen ion in distilled water is 1 chance in 10 000 000 or 1/10 000 000.
-1 × 10–7
-log of this number is -7 therefore the negative log is 7
Hydrochloric acid
-Concentration of 1/100 This is expressed as 10–2 which translates to a pH of around 2
Sodium hydroxide
also called caustic soda and an excellent substance for cleaning
greasy kitchen ovens, highly alkaline substance.
-1/1 000 000 000 000 concentration, expressed as
10–12
Common pH values
Acidic and basic substances therefore have a range of pH
values.
-pH of 0 to a pH of 14. 
Measuring pH
Cabbage indicator
The cabbage
leaves, once boiled, leaves an extract liquid, which is used as an indicator. When substance placed into clear beaker with indicator a change of colour can be observed according to pH of substance
Litmus paper
filter paper that has been
treated with indicator dyes extracted from a
lichen Lichen parmelia sulcata.
red
appearance of the paper indicates that the
solution is acidic pH<7
paper turns
purple in basic solutions pH>7
Digital meter
hand-held device which, when
placed into a solution, shows the pH reading on a digital
display.
pH and nature