Complexometric Determination of Calcium & Magnesium
Introduction
Complexometric titration refers to the titration in relation to complex components with reference to the analyte and titrant. This form of titration is essential in the determination of the mixture involving unique metal ions within a solution. In the detection of the end-point solution, it is essential to integrate the concept of an indicator marked color change. In case the reaction reaches equilibrium rapidly in relation to the addition of each titrant, any complexation reaction has the capacity to operate or apply as a volumetric technique. There is limited interference in case of the availability of the complexometric indicator with the ability to locate equivalence points with vital accuracy. In the practical aspect, the application of ETDA as a titrant is well established.
Ethylenediaminetetraacetic acid is composed of two amine groups and four essential carboxyl groups. These components have the ability to act as electron pair donors or in other cases as the Lewis bases. EDTA is a hexadentate ligand because of its ability to donate the six lone pairs of electrons in relation to the formation of coordinate covalent bonds. Despite this ability, EDTA proves to be partially ionized in practical thus the formation of the fewer covalent bonds with the metal than the expected six. Disodium EDTA usually forms four covalent bonds with the relevant metal cations within the context of pH of values ≤ 12. This is because the amine groups projecting this pH values remain protonated thus unable to donate electrons vital for the formation of the coordinate covalent bonds.
“Na2H2Y” is applicable in the analytical chemistry with the aim of denoting EDTA. “Y” in the expression represents the molecule of EDTA while the “H” denotes the number of acidic protons forming the bonds with the molecule. EDTA has the ability to form an octahedral complex with various 2+ metal cations and cations M2+ in relation to the aqueous solution. The formation constant in cases of most metal cation-EDTA complexes proves to be high thus the reason for is the application in the standardization of the metal cation solutions. This indicates that the equilibrium of the reaction is expressed as M2+ + H4Y MH2Y + 2H+
This is an illustration of the equilibrium lying far to the right. The removal of H+ is possible through the conduction of the reaction in the context of buffer solution. To execute metal cation titration with the application of EDTA, it is essential to integrate complexometric indicator. This entails the adoption of organic dye such as Murexide, Fast Sulphon Black, and Eriochrome Red B. The role of the indicator is to determine the realization of the end of the titration process. The displacement of the dye from the metal cations solution is reflected through the change of color thus the realization of the end of titration.
Results:
Experiment 1
Sample pH Color Conductivity
µs Ca2+/ Mg2+
Titration Ca2+ Titration After Boiling
3 7.03 5 7.27 27.2
23.2
23.0 28.8
26.1
12.6
4 6.41 ≤5 7.28 23.6
23.1
21.5
21.9
5 6.66 5 5.94 19.3
19.7
19.1
19.0
12.0
17.8 4.98
6 6.42 5 5.87 20.1 9.1
7 7.08 50 5.37 10.1
9.95
9.1
8.05
8 6.95 300 5.11 12.4 11.4
4.8
Valley Water 6.64 7.0 6.68 27.2
27.3
27.2
20..9
20.9
20.9 8.6
Experiment 2
Title: Complexometric Determination of Calcium & Magnesium
BOD: 1/10 (A) = 10.14 mg/L; 1/10 (B) = 10.52 mg/L; 1/20 (A) = 11.86 mg/L; 1/20 (B) = 11.85 mg/L; 1/20 (C) = 11.87 mg/L; 1/20 (D) = 11.76 mg/L; 1/50 (A) = 12.77 mg/L; 1/50 (B) = 12.20 mg/L; 1/50 (C) = 10.43 mg/L; and 1/50 (D) = 11.43 mg/L.
Calculation
Experiment 1:
Cca2+ = Vedta X Cedta X 40.08) divided by volume
Cca2+ = (22.45*9.05*40.08)/50
Cca2+ = 0.899 g/dm3
Cmg2+ = [(V1-V2) X Cedta X 24.32]/50
Cmg2+ = [(24.46-22.45)* 0.05]/50
Cmg2+ = 0.049 g/dm3
After Boiling:
Cca2+ = [Vedta X Cedta X 24.32] / 50
Cca2+ = [12.6* 0.05 * 24.32] / 50
Cca2+ = 0.306 g/dm3
Calculation for other sample:
Cca2+ = (Vedta* Cedta * 40.08) /50
Sample 4
Cca2+ = [21.7 * 0.05 * 40.08] / 50
Cca2+ = 0.869 g/dm3
Cmg = [(V1-V2) X Cedta X 24.32] / 50
Cmg = [(23.35 – 21.7) X 0.05 X 24.32] 50
Cmg = 0.04 g/dm3
Sample 5
Cca2+ = [18.27 X 0.05 X 40.08] 50
Cca2+ = 0.732 g/dm3
Cmg2+ = [( 19.33- 18.23) X 0.05 X 24.32] / 50
Cmg2+ = 0.033 g/dm3
Sample 6
Cca2+ = [9.1 X 0.05 X 40.08]/ 50
Cca2+ = 0.365 g/dm3
Cmg2+ = [(29.1-9.1) X 0.05 X 24.32] / 50
Cmg2+ = 0.268 g/dm3
Sample 7
Cca2+ = [8.575 X 0.05 X 40.08] / 50
Cca2+ = 0.344 g/dm3
Cmg2+ = [(10- 8.575) X 0.05 X 24.32]/ 50
Cmg2+ = 0.035 g/dm3
Sample 8
Cca2+ = [11.4 X 0.05 X 40.08] / 50
Cca2+ = 0.457 g/dm3
Cmg2+ = [(12.4-11.4) * 0.05 * 24.32] / 50
Cmg2+ = 0.024 g/dm3
Experiment 2:
Equation y = 0.9666 x + 304.5
R2 = 0.892
Sample 1
Y = – 0.9666 X 226.9 + 304.5
Y = 84.73 mg/ml
Sample 2
Y = – 0.9666 X 265.7 + 304.5
Y = 47.67 mg/ml
Sample 3
Y= – 0.9666 X 238.3 + 304.5
Y = 74.16 mg/ml
Sample 4
Y= – .09666 X 246.0 + 304.5
Y= 66.72 mg/ml
Sample 5
Y= – 0.9666 X 233.5 + 304.5
Y= 76.79 mg/ml
Sample 6
Y= -0.9666 X 248.8 + 304.5
Y= 64.01 mg/ml
Sample 7
Y= -0.9666 X 246.6 + 304.5
Y= 66.14 mg/ml
Sample 8
Y= -0.9666 X 240.9 + 304.5
Y= 71.65 mg/ml
Shanon
Y= -0.9666 X 246.4 + 304.5
Y= 66.33
Canal
Y= 26.343 X 0.0049 – 1.173
Y= 1.044 mg/L
Discussion & Conclusion
In the execution of the experiment, the measuring of the components of the nitrate was applicable through electrode method. There was the difference in the amount of nitrate content in relation to sample 1 and 2 in that the highest amount was registered in the former while the lowest volume was recorded in the latter. The calculation of the amount of the nitrate within the sample in the context of river Shanon was reflected as 66.33 mg/ml while 70.68 mg/ml expressed the amount of nitrate in relation to canal sample. Water sample was also vital in the measurement of the content of iron. The least amount of iron was evident in the calculation of the sample 8. There is similarity in the context of the rest of the sample. The execution of the experiment was successful thus the achievement of accurate results within the stated range
