B.Tech CSE 1st Year Engineering Chemistry Project

1. Udai Agarwal (16BCE1079)
Rudradityo Saha (16BCE1062)

2.  Alkalinity roughly refers to the amount of
bases in a solution.
 Alkalinity of the surface water constitutes of
carbonates [CO3
2-] , bicarbonates [HCO3
-] ,
hydroxides [OH-] content.
 Alkalinity in excess of alkaline earth metal
concentrations is significant in determining
the suitability of water for irrigation.

3.  Alkalinity measurements are used in the
interpretation and control of natural water
and waste water treatment processes.
 Raw domestic waste water has an alkalinity
less than or only slightly greater than that of
the water supply.

4.  Reagents –
1. HCl (0.1N)
2. Methyl Orange indicator
3. Phenolphthalein indicator
 Apparatus –
1. Conical flask
2. Burette
3. Pipette
4. Burette Stand

5. 1. Collect 20 ml water sample in a conical flask.
2. Add 3 drops of phenolphthalein indicator to
it.
3. Titrate this mixture against HCl taken in the
burette.
4. The end point of the titration is indicated by
colour change from pink to colourless.

6.  To the same solution add 3 drops of methyl
orange indicator and continue the titration.
 The end point is colour change from pale
yellow to orange.

7.  Dirty water after washing clothes
 Tap water
 Dripping water from air conditioner

8. S.No.
Volume of
water
sample
(mL)
Burette reading (mL)
Concordant value
(mL)
Initial
Final
[p] [m]
At
phenolphtha
lein end
point [p]
At methyl
orange
end point
[m]
1 20 0 0 4 0 4
2 20 4 4 7 0 3
3 20 7 7 10 0 3
Concordant titre value 0 3

9. Phenolphthalein alkalinity (mg/L) as CaCO3 =
0ppm
Methyl orange alkalinity (mg/L) as CaCO3
= ([m] ml of HCl X Normality of HCl X 50
X1000)/(Volume of water sample taken)
= (3 X 0.1 X 50 X 1000)/20
= 750ppm

10. S.No.
Volume of
water
sample
(mL)
Burette reading (mL)
Concordant value
(mL)
Initial
Final
[p] [m]
At
phenolphtha
lein end
point [p]
At methyl
orange end
point [m]
1 20 0 0 0.2 0 0.2
2 20 0.2 0.2 0.4 0 0.2
3 20 0.4 0.4 0.6 0 0.2
Concordant titre value 0 0.2

11. Phenolphthalein alkalinity (mg/L) as CaCO3 =
0ppm
Methyl orange alkalinity (mg/L) as CaCO3
= ([m] ml of HCl X Normality of HCl X 50 X
1000)/(Volume of water sample taken)
= (0.2 X 0.1 X 50 X 1000)/20
= 50ppm

12. S.No.
Volume of
water
sample
(mL)
Burette reading (mL)
Concordant value
(mL)
Initial
Final
[p] [m]
At
phenolphthal
ein end point
[p]
At methyl
orange end
point [m]
1 20 0 0 1.5 0 1.5
2 20 1.5 1.5 3 0 1.5
3 20 3 3 4.7 0 1.7
Concordant titre value 0 1.5

13. Phenolphthalein alkalinity (mg/L) as CaCO3 =
0ppm
Methyl orange alkalinity (mg/L) as CaCO3
= ([m] ml of HCl X Normality of HCl X 50 X
1000)/(Volume of water sample taken)
= (1.5 X 0.1 X 50 X 1000)/20
= 375ppm

14. S.No. Sample OH−
alkalinity
CO3
2-
alkalinity
HCO3
−
alkalinity
Total
alkalinity
1
Dirty water after
washing clothes
0 0 750 750
2
Dripping water from
air conditioner
0 0 50 50
3 Tap water 0 0 375 375

15.  All the three samples do not contain OH- ions
and CO3
2- ions but contain HCO3
− ions.
 Hence, the total alkalinity is equal to the
HCO3
− alkalinity in this case.

16.  As purity of water is determined by its alkalinity,
lowest alkalinity represents highest purity.
Hence, from the above results, it can be seen that
amongst the three samples, the water dripping
from air conditioner is most pure followed by tap
water with dirty water from washing clothes
being the least pure.
 The presence of significantly higher quantity of
bicarbonates in sample of dirty water from
washing clothes, compared to the other two
samples is due to the fact that carbon dioxide
being heavier than air easily mixes with the fibers
of clothes which is dissolved in water on
washing.

17. 1. https://en.wikipedia.org/wiki/Alkalinity
2. Engineering Chemistry Laboratory Record of
VIT University