Determination of Dissolved oxygen in the given Wastewater Sample. You are provided with a standard solution of 0.01N potassium dichromate and an approximate solution of 0.01N sodium thiosulphate.

1. DEPARTMENT OF CHEMISTRY
22CYL22 – CHEMISTRY LABORATORY
FOR MECHANICAL SYSTEMS
Prepared By
Krishnaveni K
Assistant Professor
Department of Chemistry
Kongu Engineering College,
Perundurai, Erode-638060
B.E – Automobile Engineering
Determination of Dissolved oxygen in
the given Wastewater Sample

4. Standard
K2Cr2O7
Standard
K2Cr2O7
+
dil.H2SO4
Standard
K2Cr2O7
+
dil.H2SO4
+ KI
Standard
K2Cr2O7
+
dil.H2SO4
+ KI +
Starch
Disappearance of blue
colour and appearance of
Faint green colour

6. Preparation of Water Sample
 Take 250ml of water sample + 2ml of MnSO4+
2ml of alk.KI.
 Bottle is stoppered & shaken well.
 Brown precipitate is obtained.
 The process of shaking & settling is repeated
atleast 3 times.
2ml of Con.H2SO4  yellow colour solution 
Prepared water sample.
MnSO4+
alk.KI
Brown
precipitate +
Con.H2SO4
Prepared
water sample
+ KI + Starch
Disappearance
of blue colour

8. RESULT:
The amount of dissolved oxygen present in the
given wastewater sample ---------------PPM

9. VIVA - VOCE QUESTIONS
1. What is dissolved oxygen?
2. What is meant by Iodometry?
3. What is redox reaction?
4. Name the oxidizing and reducing agent used in the experiment.
5. What is the role of oxidizing and reducing agent used in the experiment.
6. What is winkler’s reagent?
7. Write the permissible limit of dissolved oxygen.
8. How do to you prepare the water sample?
9. Write the colour of starch-iodo complex.
10. Name the indicator used in this experiment.

10. REFERENCES:
 1.Palanisamy P.N., Manikandan P., Geetha A.& Manjula Rani K,
“Chemistry lab Manual”, 2023.
1-Aug-23

11. 1-Aug-23
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YOU
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