This document summarizes a chemistry lab experiment on estimating the amount of copper in a solution using iodometric titration. The objectives are to determine the amount of copper in a copper salt solution and study oxidation-reduction titration. Standard sodium thiosulfate solution is used to titrate iodine liberated from the reaction of copper solution, potassium iodide, and acetic acid. Calculations are shown to find the molarity of copper in the original solution based on the titration results. The amount of copper determined in 1 liter of the supplied copper sulfate solution was 0.978 grams.

1. Course Title: Chemistry Lab
Course Code: CHEM 102
Green University of Bangladesh
Dept. Of EEE
Presented by :
Mr. Asif kabir
ID: 232001014
Mr. Maruf Ahmed Joy
ID: 232001013
Presented To :
Jagannath Biswas
Associate Professor,
Dept of Textile
Green University Of Bangladesh
Exp name: Estimation of Copper Contained in a
Supplied Solution by Iodometric Method

2. 2
Contents
01 Objectives
02 Theory
03 Apparatus
04 Procedure
05 Table with Calculation
05 Result

3. Objectives
3
• To study the amount of copper present in copper salt solution.
• To study oxidation reduction titration.
• To study the percentage of copper present.

4. Theory
4
• In this experiment, the amount of copper in a copper salt solution is determined.
The reaction that occurs here is oxidation and reduction reaction as well as
iodometric reaction.
• This reaction is iodometric because iodine is got from KI. The reaction takes place
in two steps:
Cu(2+) + KI + H+ = I2 +……
Na2S2O3 + I 2 = Na2S4O6 + ……
• Here, for the first part of the experiment, the basis of the volumetric measurement
is that one equivalent weight of an oxidizing agent will completely react with one
equivalent weight of a reducing agent.

5. Theory
5
• 1000 ML 1M Na2S2O3 react with 63.54g Cu2+
(Average volume) (Exp -3)m react with [(63.54* average * Ex4) / 1000] Cu2+
• 10mL Cu solution contain = x g cu2+
1000mL Cu solution contain = x * 100 g/L
= y g/L
• So, the weight of copper in the supplied solution may then be easily calculated
using the above relation.

6. Apparatus
6
• 1. Conical flask
• 2. Burette
• 3. Pipette
• 4. Volumetric flask
• 5. Stand
• 6. Funnel
Name of the chemicals used:
1. Na 2 S 2 O 3 solution
2. K 2 Cr 2 O 7 solution
3. KI solution
4. NaHCO 3
5. HCl solution (concentrated)
6. Distilled water
7. CuSO 4 solution
8. CH 3 COOH solution
9. NH 4 CNS solution
10. Starch (Indicator)

7. Procedure 7
• Standardization of Sodium Thiosulphate solution as experiment no. 04
• Pipette out 10 ml of supplied copper salt solution into a conical flask. Add a few drop
of dil. NaOH or NaHCO 3 or Na 2 CO 3 . A pale greenish principate should appear.
• Dissolve the principate by adding few drop of acetic acid (CH 3 COOH). Add about 10
ml of 10% potassium iodide (KI) solution and titrate the liberated iodine against the
standard thiosulphate solution (standardized previously) until the brown color of iodine
changes to light yellow.
• Add 1 ml of starch solution and continue titration till the blue color begins to fade. Now
add few drops of 10% Ammonium thiocyanate solution and continue titration until the
blue color is just discharged.
• Calculate the amount of copper present in one liter of the supplied solution.

8. Table with Calculation 8
• Table 1: Data for standardization of Sodium Thiosulphate solution with standard 0.02 M potassium
Dichromate Solution =
NO. of
obs
Volume of
k2Cr2O7
(ml)
Initial
(ml)
Final
(ml)
Volume of
Na2S2O3
ml
Average
Volume
Of
Na2S2O3
(ml)
Strength of
Na2S2O3
(M)
1 10 0 12.4 12.4
2 10 12.4 25.2 12.8 12.8667 0.01554
3 10 25.2 38.6 13.4

9. Table with Calculation 9
• Table 2: Determination of Cu 2+ content in supplied solution by standard ……M potassium Dichromate
Solution:
NO. of
obs
Volume of
Cu2+
Solution
(ml)
Initial
(ml)
Final
(ml)
Volume of
Na2S2O3
ml
Average
Volume
Of
Na2S2O3
(ml)
Strength of
Cu2+
Solution
(M)
1 10 0 10.8 10.8
2 10 10.8 20.9 10.1 10 0.978
3 10 20.9 31 9.1

10. Result 10
• The amount of copper (in gm) present in the supplied CuSO 4 solution (per litre) is : Wcu =
0.978gm.
• Discussion:
1. Sodium thiosulphate makes for an inexpensive, safe and effective reducing agent to react
with I2. Since starch turns to a dark blue in the presence of I2, then back to white
when the I2 is depleted, starch makes a good indicator for the endpoint of this reaction.
2. Potassium iodide, KI, is readily available in high purity.
3. A precise and stable reducing agent, sodium thiosulfate (Na2S2O3), is available to react
with the iodine.
4. Loss of iodine by evaporation from the solution. This can be minimized by having a large
excess of iodide in order to keep the iodine tied up as tri-iodide ion.

11. Thank You