Titration:
It
is a method of finding the concentration of a solution by reacting it with a
standard solution and measuring their corresponding volumes.
Standard
solution:
A
solution of accurately known concentration.
**Preparing a standard
solution:
250
cm3 , 0.1 moldm-3 of Na2CO3
solution is to be made.
Na2CO3 is a primary standard
i.e. a pure , stable, soluble, solid compound. It’s mass can be measured and
can be dissolve completely in water.
a) Apparatus
required:
7) Distilled water 8) Stirrer/ Glass rod 9)
Dropper.
b) First
calculating the required mass of Na2CO3 to make the standard
solution:
No. of moles of Na2CO3 :
(0.1X250X10-3 ) moles [No.
of moles= Conc. in moldm-3 X Volume in cm3 X 10-3]
Mass of Na2CO3 :
(0.1X250X10-3)X(46+60)
[ Mass= no. of moles X Molar Mass]
Mass of Na2CO3 :
2.65g is required for making a standard
solution.
c) Procedure:
Step 1: -
Accurately measuring the mass of the Na2CO3 solute in
weighing bottle.
- Placing the empty weighing
bottle on the top pan balance and reading it’s mass zero by pressing
tare/ zero button.
-Then taking reading of the mass
of Na2CO3 by placing it over the weighing bottle on the
top pan balance.
Step 2: -
Transferring Na2CO3 to beaker by using distilled water.
- Transferring Na2CO3
solute to the beaker by washing Na2CO3 from weighing
bottle with
distilled water. Making sure
that every little bit of Na2CO3 is washed down to the
beaker with
distilled water.
Step 3: -
Dissolving all of the Na2CO3 in distilled water by using
stirrer/ glass rod in beaker.
Step 4: -
Taking a volumetric flask of 250 cm3 and placing a funnel on top
opening of
volumetric flask.
- Now transferring Na2CO3
solution to the volumetric flask. Pouring Na2CO3 along
the side of
the glass stirrer to avoid
spillages. Slowly transferring all the solution from beaker to the
volumetric flask.
Step 5 :- Now
rinsing the glass rod with distill water to the volumetric flask.
The beaker and
the funnel is rinsed thoroughly with distilled water and washing of stem of the
volumetric flask is allowed to run down into the flask.Carrying out
this step carefully since this is the most essential step.
 |
| Now rinsing the glass rod with distill water to the volumetric flask. |
 |
| The beaker is rinsed thoroughly with distilled water. |
 |
| Pouring the solution of Sodium Carbonate into the volumetric flask. |
 |
| The funnel is rinsed thoroughly with distilled water and washing of stem of the volumetric flask is allowed to run down into the flask. |
Step 6:- Now carefully
bringing the lower meniscus close to the graduation mark on the volumetric
flask by giving distilled water. Stopping at about 1 cm3 away from
the graduation mark.
Then carefully
bringing lower meniscus to the graduation mark by adding distilled water drop
wise with the help of dropper. Eyes should be level with graduation mark.
Step 7: - A
stopper is placed over the volumetric flask and inverted several times to
ensure homogeneous(uniform) solution in volumetric flask which is very
essential while carrying out titration.
Shaking,
swirling the volumetric flask won’t help to make homogeneous solution because
of the shape of the volumetric flask.
Then labeling
the flask containing the primary standard solution of Na2CO3.
Precaution:
1) Wear gloves
1) Wear gloves
2) Eye protective gear.
3) Solute shouldn't get loss while transferring from weighing bottle.
4) Solution shouldn't spill from beaker while transferring to volumetric flask.
5) Rinsing every pieces of apparatus with distilled water is essential and pour that solution to volumetric flask
4) Solution shouldn't spill from beaker while transferring to volumetric flask.
5) Rinsing every pieces of apparatus with distilled water is essential and pour that solution to volumetric flask
carefully.
6) Eye level should be exactly perpendicular to the graduation mark of the volumetric flask.perpendicular to the graduation mark.
6) Eye level should be exactly perpendicular to the graduation mark of the volumetric flask.perpendicular to the graduation mark.
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