Monique Gray and Jared Poist Real World Experiment
Quantitative Analysis
Real-World Experiment: EDTA Titration of Hardness of Water
Introduction
The purpose of this experiment was to use the EDTA titration technique to determine the hardness of Spring water and tap water and compare the results to a previous experiment done on the hardness of tap water.
Procedure
-
-
-
-
-
-
-
-
Prepared 0.1M CaCl
2
solution and 0.01 EDTA solution
Standardized the EDTA solution with the CaCl
2
solution
Calibrated a pH meter with three standard buffer solutions
Calibrated a buffer solution to pH 10
Added 3mL of CaCl
2
, into a 250mL flask with 5 drops of calmigite indictor, and 5mL of ammonia buffer
Completed three trials and recorded the results.
Added 25mL of water sample, 5 drops calmigite indicator, and 3mL of ammonia buffer.
Recorded three good trials and repeated last step for the next water sample.
Data
Mass of EDTA: 0.9312g
Trial #
1
2
3
Mass of CaCO
3
: 1.010g
Calculation for preparing EDTA solution and CaCl
2
solution
372.24𝑔
1
𝑥
0.01 𝑀
1 𝐿
𝑥
0.250𝐿
1
= 0.9306 𝑔 𝐸𝐷𝑇𝐴
0.1𝑀 𝐶𝑎𝐶𝑙
2
1
𝑥
0.100𝐿
1
𝑥
1 𝑚𝑜𝑙 𝐶𝑎𝐶𝑂
3
1 𝑚𝑜𝑙 𝐶𝑎𝐶𝑙
2
𝑥
100.09𝐶𝑎𝐶𝑂
3
1 𝑚𝑜𝑙
= 1.009𝑔 𝐶𝑎𝐶𝑂
3
EDTA Added (mL)
15.20mL
14.0mL
15.0mL
Molarity of EDTA
0.01973M
0.0214M
0.0200M
EDTA titration with Filtered Water
Trial #
1
2
3
Amount Of Water
Sample (mL)
25mL
25mL
25mL
Amount EDTA
Added (mL)
1.9mL
1.7mL
2.01mL
Molarity Of Ca
0.0015504 M
0.0013872M
2+
0.00164016M
Ppm of Ca 2+
62.1370ppm
55.5970ppm
65.7343ppm

Monique Gray and Jared Poist Real World Experiment
Trial #
1
2
3
Amount of Water
Sample (mL)
25mL
25mL
25mL
Amount of EDTA
Added (mL)
1.20mL
1.20mL
1.10mL
Molarity of Ca
0.0009792M
0.0009792M
0.0008976M
2+ Ppm of Ca 2+
39.244ppm
39.244ppm
35.974ppm
Trial #
Conclusion
1
2
3
Amount of Water
Sample (mL)
25mL
25mL
25mL
Amount of EDTA
Added (mL)
2.68mL
2.31mL
2.25mL
Molarity of Ca
0.00236M
0.00203M
0.00198M
2+ Ppm of Ca 2+
94.584ppm
81.358ppm
79.354ppm
We had originally hypothesized that tap water will have a higher hardness content than both spring water and filtered water. Also, we hypothesized that filtered water would have a higher hardness than spring water. We found that both hypothesizes held true in both cases. The only error I have experienced in this lab and in the previous EDTA titration lab was that when trying to obtain a 0.01EDTA solution when standardized it always came out to be around 0.02M EDTA. I’m think this could have been a simple calculated error or just the ratio was a little off. This problem I have seen this problem class wide.