EXPERIMENT NO. 04 (a)
OBJECT: Hardness of standard hard water is 1000 ppm. To determine the
total hardness of given water sample using EDTA as an intermediate solution and
Eriochrome Black-T as an indicator.
OBSERVATION TABLE:
[A] Titration
between standard hard water (SHW) sample and EDTA solution
S. No. |
Volume of standard hard water (SHW) (mL) |
Burette Reading (mL) |
Concordant Reading (X) (mL) |
|
Initial |
Final |
|||
1 |
20 |
0.0 |
9.2ml |
9.2ml |
2 |
20 |
0.0 |
|
|
3 |
20 |
0.0 |
|
[B] Titration
between unknown hard water (UHW) and EDTA solution
S. No. |
Volume of unknown hard water (UHW) (mL) |
Burette Reading (mL) |
Concordant Reading (Y) (mL) |
|
Initial Final |
||||
1 |
20 |
0.0 |
19ml |
19ml |
2 |
20 |
0.0 |
|
|
3 |
20 |
0.0 |
|
CALCULATION:
[A]
Standardization of EDTA
Hardness
of standard hard water (SHW) = 1000 ppm
So, 1000 mL of SHW contains
= 1000 mg CaCO3
Thus,1 mL of SHW contains =
1000/1000 mg CaCO3
= 1mg CaCO3
9.2 mL EDTA consume = 20 mL SHW = 20 mg CaCO3
Hence, 1 mL EDTA is
equivalent to = 20/9.2 mg CaCO3
[B] Hardness of unknown hard water (UHW) sample
20 mL
UHW consumes = 19 mL EDTA = 19×(20/9.2) mg CaCO3
Thus, 1 mL UHW = 19/20 x
20/9.2 mg CaCO3
= 19/9.2 mg CaCO3
Hence, 1000 mL of UHW =
19/9.2×1000 mg/L CaCO3
Total hardness
= 2065.21 ppm
RESULT: Total hardness of given unknown hard water is 2065.21 ppm.
EXPERIMENT NO. 04 (b)
OBSERVATION TABLE:
[A] Titration
between standard hard water (SHW) and EDTA
S. No. |
Volume of standard hard water
(SHW) (mL) |
Burette Reading (mL) |
Concordant Reading (X) (mL) |
|
Initial |
Final |
|||
1 |
20 |
0.0 |
9.2ml |
9.2ml |
2 |
20 |
0.0 |
|
|
3 |
20 |
0.0 |
|
[B] Titration
between unknown hard water (UHW) and standardized EDTA solution
S. No. |
Volume of unknown hard water (UHW) (mL) |
Burette Reading (mL) |
Concordant Reading (Y) (mL) |
|
Initial Final |
||||
1 |
20 |
0.0 |
19ml |
19ml |
2 |
20 |
0.0 |
|
|
3 |
20 |
0.0 |
|
[C] Titration
between boiled hard water (BHW) and standardized EDTA solution
S. No. |
Volume of boiled water (BHW)
(mL) |
Burette Reading (mL) |
Concordant Reading (Z) (mL) |
|
Initial |
Final |
|||
1 |
20 |
0.0 |
14.1ml |
14.1ml |
2 |
20 |
0.0 |
|
|
3 |
20 |
0.0 |
|
CALCULATION:
[A] Standardization of EDTA
Hardness of standard hard water (SHW) =
1000 ppm
So, 1000 mL of SHW contains = 1000 mg CaCO3
Thus, 1 mL of SHW contains = 1000/1000 mg CaCO3 = 1mg CaCO3
9.2 mL EDTA consume = 20 mL SHW = 20 mg CaCO3
Hence, 1 mL EDTA is equivalent to = 20/9.2 mg
CaCO3
[B] Hardness of unknown hard water (UHW) sample
20 mL
UHW consumes = 19 mL EDTA = 190x 20/9.2 mg CaCO3
Thus, 1 mL UHW = Y/20 x 20/X
mg CaCO3 = 19/9.2 mg CaCO3
Hence, 1000 mL of UHW = Y/X
x 1000 mg/L CaCO3
Total hardness = 2065.21 ppm
[C] Hardness of boiled hard water (BHW) sample
20 mL BHW consumes = Z mL EDTA = 14.1 x 20/9.2 mg
CaCO3
Thus, 1 mL BHW = Z/20 x 20/X mg CaCO3 = 14.1/9.2 mg CaCO3
Hence, 1000 mL of BHW =
14.1/9.2 x 1000 mg/L CaCO3
Permanent hardness = 1532.60 ppm
Temporary Hardness = Total
Hardness-Permanent Hardness = 2065.21-1532.60
= 532.61 ppm
RESULT:
Hardness of given water sample is-
Total hardness = 2065.21ppm Permanent hardness =1532.60ppm Temporary hardness = 532.61ppm
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