43
4. If the solution becomes pink, it be titrated
with 0.02 N H 2 SO 4 (taken in a 50-ml burette),
until a clear solution is obtained.
5. Volume (ml) of 0.02 N H 2 SO 4 required in phenolphthalein titration be recorded.
6. Next, 2–4 drops of methyl orange indicator
solution is added to the same solution in the
Erlenmeyer flask.
7. Titrated again with the same 0.02 N H 2 SO 4
until the solution turns pink orange.
8. Volume (ml) of 0.02 N H 2 SO 4 required in the
methyl orange titration is also recorded.
The data be recorded in the following table:
Phenolphthalein Titration
Obs.
Initial burette
reading
Final burette
reading
Difference
No.
(ml)
(ml)
(ml)
1
2
3
Methyl Orange Titration
Obs.
Initial burette
reading
Final burette
reading
Difference
No.
(ml)
(ml)
(ml)
1
2
3
3.2.4.3 Result
1. 10 times the volume (ml) of 0.02 N H 2 SO 4
required in phenolphthalein titration = phenolphthalein alkalinity (PA) in ppm (mg/l)
2. 10 times the volume (ml) of 0.02 N H 2 SO 4
required in methyl orange titration = methyl
orange alkalinity (MOA) in ppm.
3. Total alkalinity (TA) is the sum of PA and MOA
when both have values to contribute to the same.
3.2.5 Specific Conductivity
Conductivity of a water sample is its ability to
carry electric current which depends on total
concentration of ionised substances, mobility of
each of such ions, their valences, etc. On the
other hand, specific conductivity means conductivity of a segment of a particular solution having a length of 1 cm and a cross-sectional area of
1 cm
2
. Organic compounds contribute very little
to conductivity because they are mostly nonionic. Freshly prepared DW has conductivity of
0.5–2.0 micromhos/cm which may increase to
about 4.0 micromhos/cm on storage due to
absorption of CO 2 from air. Conductivity reflects
the characteristics of the water supplied.
Conductivity of a flowing stream could be
recorded continuously in situ along with other
parameters, e.g. DO, pH and temperature.
However, the monitoring equipments are required
to be frequently checked to avoid electrode
misleading.
There are different kinds of conductivity
bridges manufactured by various companies. The
Digital Direct Reading Conductivity meter is
designed for measuring the specific conductivity
of a solution by using a conductivity cell. It
enables to measure the conductivity, without
manual balancing, and the specific conductivity
is read directly on a digital panel.
3.2.5.1 Principle
A conductance cell and a Wheatstone bridge is
used for measuring the conductivity. The conductance of a solution increases with temperature at
a rate of approx. 2 % per degree Celsius. KCl has
a lower temperature coefficient of conductivity
and hence is used in the cell. For precise works,
conductivity be determined at 25 °C.
The main feature of a standard digital conductivity meter is that it avoids the conventional
method of manual balancing by employing a selfbalancing ratio-transformer bridge technique. A
highly stable oscillator powers the bridge. The
current through the conductivity cell passes
through one winding of the radio transformer.
The other winding output is fed to a selective
high gain amplifier, the output of which drives a
current in the third winding, in such a way, that,
the flux in this winding opposes the flux in the
first winding. This goes on until both the fluxes
cancel each other and consequently the detector
output will be almost zero. The output of the
3.2 Chemical
4. If the solution becomes pink, it be titrated
with 0.02 N H 2 SO 4 (taken in a 50-ml burette),
until a clear solution is obtained.
5. Volume (ml) of 0.02 N H 2 SO 4 required in phenolphthalein titration be recorded.
6. Next, 2–4 drops of methyl orange indicator
solution is added to the same solution in the
Erlenmeyer flask.
7. Titrated again with the same 0.02 N H 2 SO 4
until the solution turns pink orange.
8. Volume (ml) of 0.02 N H 2 SO 4 required in the
methyl orange titration is also recorded.
The data be recorded in the following table:
Phenolphthalein Titration
Obs.
Initial burette
reading
Final burette
reading
Difference
No.
(ml)
(ml)
(ml)
1
2
3
Methyl Orange Titration
Obs.
Initial burette
reading
Final burette
reading
Difference
No.
(ml)
(ml)
(ml)
1
2
3
3.2.4.3 Result
1. 10 times the volume (ml) of 0.02 N H 2 SO 4
required in phenolphthalein titration = phenolphthalein alkalinity (PA) in ppm (mg/l)
2. 10 times the volume (ml) of 0.02 N H 2 SO 4
required in methyl orange titration = methyl
orange alkalinity (MOA) in ppm.
3. Total alkalinity (TA) is the sum of PA and MOA
when both have values to contribute to the same.
3.2.5 Specific Conductivity
Conductivity of a water sample is its ability to
carry electric current which depends on total
concentration of ionised substances, mobility of
each of such ions, their valences, etc. On the
other hand, specific conductivity means conductivity of a segment of a particular solution having a length of 1 cm and a cross-sectional area of
1 cm
2
. Organic compounds contribute very little
to conductivity because they are mostly nonionic. Freshly prepared DW has conductivity of
0.5–2.0 micromhos/cm which may increase to
about 4.0 micromhos/cm on storage due to
absorption of CO 2 from air. Conductivity reflects
the characteristics of the water supplied.
Conductivity of a flowing stream could be
recorded continuously in situ along with other
parameters, e.g. DO, pH and temperature.
However, the monitoring equipments are required
to be frequently checked to avoid electrode
misleading.
There are different kinds of conductivity
bridges manufactured by various companies. The
Digital Direct Reading Conductivity meter is
designed for measuring the specific conductivity
of a solution by using a conductivity cell. It
enables to measure the conductivity, without
manual balancing, and the specific conductivity
is read directly on a digital panel.
3.2.5.1 Principle
A conductance cell and a Wheatstone bridge is
used for measuring the conductivity. The conductance of a solution increases with temperature at
a rate of approx. 2 % per degree Celsius. KCl has
a lower temperature coefficient of conductivity
and hence is used in the cell. For precise works,
conductivity be determined at 25 °C.
The main feature of a standard digital conductivity meter is that it avoids the conventional
method of manual balancing by employing a selfbalancing ratio-transformer bridge technique. A
highly stable oscillator powers the bridge. The
current through the conductivity cell passes
through one winding of the radio transformer.
The other winding output is fed to a selective
high gain amplifier, the output of which drives a
current in the third winding, in such a way, that,
the flux in this winding opposes the flux in the
first winding. This goes on until both the fluxes
cancel each other and consequently the detector
output will be almost zero. The output of the
3.2 Chemical