Estimation of Bronze by Titration.

1. To estimate a sample
of Bronze
- MAITREYI KAUSHIK

2. AGENDA
1. Introduction
a. Alloys
b. Bronze
c. Iodometric Titration
d. Sodium thiosulphate
e. Starch
2. Materials Required
a. Apparatus
b. Chemicals
3. Procedure
a. Preparation of solutions
b. Standardization of Sodium
thiosulphate
c. Estimation of Bronze
4. Sample Observations and Calculations

3. Alloys
Better properties
03
Harder than
components
02
Homogenous
mixture
01

4. Copper
67% - 95%
Tin
4% - 12%
Zinc and Lead
Sometimes
Bronze

5. Iodometric Titration
Indirect method 2 Reactions
Iodine first
oxidized and
then reduced
More common

6. Sodium thiosulphate
White or colourless
Crystalline
Dissolves well
Excellent shelf life
Titrant in Iodometry
Estimation of Chlorine content

7. Starch
Reference: Charles E Ophardt
(2003). Starch-Iodine. Virtual
Chembook. Elmhurst College.
http://chemistry.elmhurst.edu
/vchembook/548starchiodine
.html

8. Materials Required
● Burette
● Pipette
● Beakers
● Conical flask
● Volumetric flasks
● Silica crucible
Apparatus
● Sodium thiosulphate (Na2S2O3)
● Copper sulphate (CuSO4.5H2O)
● Bronze sample
● Sodium bicarbonate (NaHCO3)
● Acetic acid (CH3COOH)
● Potassium iodide (KI)
● Starch
● c. HNO3
Chemicals

9. Procedure
Preparation of
solutions
Standardization of
Sodium
thiosulphate
solution
Titration of
sample
solution
01 03
02

10. Preparation of Solutions
Copper sulphate
solution
Bronze solution
Sodium thiosulphate
solution
Bronze + Water + c. HNO3 + stir → Clear solution
3Cu + 8H+ → 3Cu2+ + 2NO + 4H2O
4Sn + NO3- + 10H+ → 4Sn2+ + NH4
+ + 3H2O
Heat → brown fumes
Sn + 4NO3
- + 4H+ → H2SnO3 + 2NO2 + H2O
Water → warm → white precipitate → Filtration
Filtrate + water → 250 mL (contains Cu)
Residue → contains Sn

11. Standardization of Sodium thiosulphate
Starch added → Blue-black colour
Na2S2O3 solution added →
Colourless solution
KI → Kept in dark (2 min)
Na2S2O3 solution added → Pale
yellow colour
CuSO4 solution + NaHCO3 →
Faint precipitate
Acetic acid → clear solution

12. Estimation of Bronze
Same procedure as that followed in the
standardization of Sodium thiosulphate
solution
Precipitate → Silica crucible → Hot
furnace (15-20 min) → Cooled at room
temperature → Tin oxide weighed
Solution containing Cu
Filtrate containing Sn

13. SAMPLE
OBSERVATIONS
AND
CALCULATIONS

14. Molarity of CuSO4 solution

15. Standardization of Na2S2O3 solution
Molarity of Na2S2O3 solution

16. Titration of Sample solution
containing Copper
Molarity of Cu in solution Strength of Cu

17. Observations from Gravimetric
analysis of Sn
Calculations for the amount of Sn

18. Percentage of Cu in the Sample
Percentage of Sn in the Sample

19. References
1. Pabitra Kumar Mani (2014). Permanganometry, iodometry in
analytical technique. Slideshare
2. Vogel, Arthur I. (Arthur Israel). (1989). Vogel's textbook of
quantitative chemical analysis. Harlow, Essex, England : New York
:Longman Scientific & Technical ; Wiley
3. The Editors of Encyclopaedia Britannica. Bronze. Britannica.
Retrieved January 24, 2021 from
https://www.britannica.com/technology/alloy
4. Charles E Ophardt (2003). Starch-Iodine. Virtual Chembook.
Elmhurst College.
http://chemistry.elmhurst.edu/vchembook/548starchiodine.html

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Thank you!
MAITREYI KAUSHIK
M.Sc. (F) Chemistry
Inorganic Chemistry
Group 4
Roll. No. 19024746007