This document outlines quick test methods for determining the concentrations of chromium and chloride in water samples. It describes: 1. The analytical process to determine chromium using acid diphenylcarbazide indicator solution and spectrophotometry. Standards and samples are prepared and their absorbance measured to create a calibration curve relating absorbance to chromium concentration. 2. The analytical process to determine chloride using potassium chromate indicator solution and silver nitrate titration. Sodium chloride and water samples are titrated with silver nitrate and the volumes recorded. 3. Potential ways to package the reagents for portability, including using pill containers and glass ampoules. It also discusses the possibility of developing a smartphone app using the camera

1. Quick tests for
determining Cr y Cl-

2. Inde
x
1.Introduction. What are our objectives? What
we pretend?
2.Analytical process to determine Cr
3.Analytical process to determine Cl-
4.How can we package our product?
5.Roles of the members of group

3. objectives?
What we pretend?
QUICK TEST
➔ Quick cinetic reaction
➔ Known analytical process
➔ None heating requirement
➔ A limit value known
➔ Known the expiration of the components and the
requirements of this

4. Introduction. What are our
objectives?
What we pretend?
Sample with our
analyte with
unknown
concentration
A specific quantity
of moles that are
the necessary to
react with the
limit value
An indicator that
indicates qualitatively,
if you are above or below
the limit value
1 2 3

5. Analytical process to
determine Cr(VI) in water

6. EQUIPMENT AND REAGENTS
1. Acid diphenylcarbazide (indicator solution)
2. Potassium dichromate (stock standard solution)
3. Deionised double distilled water
4. Spectrophotometer for VIS (540 nm) and spectrophotometer cells
5. Volumetric materials (calibrated flasks, beakers, pipettes...)
Analytical process to determine Cr(VI) in water

7. REAGENTS
1. Acid diphenylcarbazide indicator solution
0.2 g diphenylcarbazide
+
100 mL EtOH
+
400 mL H2SO4 1/10
refrigerated!!

8. REAGENTS
2a. Potassium dichromate 0.1 g/L (stock standard solution)
0.374 g K2Cr2O7
+
Deionised double
distilled water

9. REAGENTS
2b. Potassium dichromate 0.001 g/L (standard solution)
10 mL K2Cr2O7
0.1 g/L
K2Cr2O7
0.001 g/L
K2Cr2O7

10. EQUIPMENT
Spectrophotometer VIS (540 nm)

11. PROCESS
1. Prepare the solutions (as seen before)
2. Prepare the samples for the calibration curve
3. Let the samples stand for 10 min for color development
4. Measure the absorbance of the samples in the spectrophotometer at 540 nm
5. Trace the calibration curve by plotting the absorbance against the quantity of
Cr(VI) (in ppm)
Analytical process to determine Cr(VI) in water

12. PROCESS
2. Prepare the samples for the calibration curve
3. Let the samples stand for 10 min for color development
mL

13. PROCESS
4. Measure the absorbance in the spectrophotometer at 540 nm
mL

14. PROCESS
5. Trace the calibration curve: A vs ppm Cr(VI)

15. Analytical
process to
determine Cl-

16. EQUIPMENT AND REAGENTS
1.Potassium chromate (indicator solution)
2.Silver nitrate 0,0141M (standard
solution)
3.Sodium chloride 0,0141M (standard
solution)
4.Materials commonly used in a laboratory
(volumetric flasks…)
5.Burette

17. REAGENTS
1. Potassium Chromate indicator
solution
50 g K2CrO4
+
AgNO3
+
Distilled water (1L)

18. 2. Silver nitrate (0,0141 M)
2,395 g AgNO3
+
1000 mL distilled
water

19. 3. Sodium Chloride (0,0141 M)
140 º C

20. 824 mg NaCl
+
1000 mL distilled
water

21. PROCESS
1.Silver nitrate titration
10 mL NaCl (0,0141 M)
+
1 mL indicator solution
(K2CrO4)

22. 10 mL NaCl (0,0141 M)
+
1 mL indicator solution
(K2CrO4)

23. 2. Sampling titration
10 mL water
+
1 mL indicator solution
(K2CrO4)

24. 10 mL water
+
1 mL indicator solution
(K2CrO4

25. 3. White titration
100 mL distilled water
+
1 mL indicator solution
(K2CrO4)

26. 100 mL destilled water
+
1 mL indicator solution
(K2CrO4)

27. RESULTS

29. 1. Sampling
2. Indicator
3. AgNO3

30. How can we package our
product? Cl-
Potassium Chromate Silver Nitrate
Container High density polyethylene (glass ampoule) Container that does not let the light pass
Volume (mL) 1 1

31. How can we package our
product? Cr
Diphenylcarbazide Sulfuric acid 1:10 Ethyl alcohol
Container pill
Container that does not
let the light pass (glass)
High density
polyethylene
Volume
(mL)
0,0200 g 60 10

32. Qualitative results but we can
do more…
We can use the technology
Our smartphones… apps

33. What we need for that?
● Good illumination
● A camera
● Database that have a relation between
colours and concentration
● A program that make it automatically

34. [Cl-]
mg/L
R G B
100 63 7 3
125 81 18 3
150 83 25 13
175 94 40 12
200 109 63 30
225 139 117 60
250 146 146 58
300 151 146 61
350 136 144 51
400 147 146 62
450 144 142 65
500 148 146 63
550 148 146 61
600 152 146 58

35. 5. Roles of the members of
group
- Lucía Mones Iglesias: Group coordinator, planning of
chloride analysis + laboratory work
- Eva Fernández Zapico: Planning of chrome analysis +
laboratory work
- Eva M. García Ibán: Planning of hardness of water +
laboratory work
- Alejandro Fernández: Laboratory work

36. The End