(c) If the water turns gray-blue, blue or green, the free
acidity is zero.
(d) If the water turns pink, add sodium hydroxide standard
solution dropwise (with constant swirling of the mixing bottle and
counting of the drops) until the water just begins to turn gray-blue.
The dropper must be held verical.
(e) The free acidity in mg/l is equal to 6.88 times the number
of drops of Sodum Hydroxide Standard Solution required to titer.
(4) Total Acidity Test.
(a) The directions for total acidity are the same as for free
acidity except that one drop of phenolphthalein indicator solution is
used instead of brom cresol green-methyl red, and the tiration is
carried from colorless to the first slight pink color.
(b) If the sample turns pink on addition of the indicator only,
the total acidity is zero.
Chloride Test Kit High Range 1,000 to 20,000 mg/l (fig. 2-6).
(1) Chlorides are present in all potable water supplies and in
sewage, usually as a metallic salt.
When sodium is present in drinking
water, chloride concentrations in excess of 250 mg/l give a salty taste.
If the chloride is present as a clacium or magnesium salt, the taste
detection level may be as high as 1000 mg/l chloride.
(a) Chloride is essential in the diet and passes through the
digestive system unchanged to become one of the major components of raw
The wide use of zeolite in water softeners also contributes a
large amount of chloride to sewage and wastewaters.
(b) High chloride concentrations in water are not known to have
toxic effects on man, though large amounts may act corrosively on metal
pipes and be harmful to plant life.
The maximum allowable chloride
concentration of 250 mg/l in drinking water has been established for
reasons of taste rather than as a safeguard against physical hazard.
Do not allow reagents to come in contact with skin
Do not ingest solutions containing Silver
Nitrate and Methanol.
May be fatal if swallowed.
May cause permanent blindness.
are corrosive or poisonous or both.