Acids produce
hydrogen ions, H+(aq), in solution
Bases generate
hydroxide (OH–) ions in water. Bases which are soluble in water are called
alkalis.
Mixing an acid
or base with water results in decrease in the concentration of ions (H3O+/OH–)
per unit volume. Such a process is called dilution
A scale for
measuring hydrogen ion concentration in a solution, called ph scale has been
developed. The p in ph stands for ‘potenz’ in German, meaning power. On
the ph scale we can measure ph generally from 0 (very acidic) to 14 (very
alkaline).
Our body works
within the ph range of 7.0 to 7.8. When ph of rain water is less than 5.6, it
is called acid rain.
Tooth decay
starts when the ph of the mouth is lower than 5.5. Tooth enamel, made up of
calcium phosphate is the hardest substance in the body. It does not dissolve in
water, but is corroded when the ph in the mouth is below 5.5. Bacteria present
in the mouth produce acids by
Degradation of
sugar and food particles remaining in the mouth after eating.
Bleaching powder is represented
as caocl2
Na2CO3.10H2O (washing soda)
On heating gypsum at 373 K, it
loses water molecules and becomes calcium sulphate hemihydrate caso4.1/2H2O
This is called Plaster of Paris.
When an acid reacts
with a metal, hydrogen gas is evolved and a corresponding salt is formed.
