2. E
F
F
E
C
T
S
With hard water, soap solutions form a white
precipitate
(soap
scum)
instead
of
producing lather, because the 2+ ions destroy
the surfactant properties of the soap by forming
a solid precipitate (the soap scum). A major
component of such scum is calcium stearate,
which arises from sodium stearate, the main
component of soap:
2 C17H35COO- + Ca2+ → (C17H35COO)2Ca

3. TYPES OF HARDNESS
TEMPORARY HARDNESS
PERMANENT HARDNESS
Caused by the presence of dissolved
bicarbonate chemicals. When
dissolved these minerals yield
calcium and magnesium cat ions and
carbonate and bicarbonate anions . It
can be removed by either boiling the
water or by addition of lime through
the softening process.
Caused by the presence of calcium
sulphate and magnesium sulphate
which do not precipitate out while
boiling. Ions causing permanent
hardness can be removed by using a
water softener or Ion exchange
column.