EXPERIMENT - 2
DETERMINE THE PRODUCT OF A REDOX REACTION
REACTION OF BROMATE AND HYDROXYLAMMONIUM IONS
EXPERIMENT PERFORME03 OCTOBER, 2012
REPORT SUBMITTED10 OCTOBER, 2012
SUBMITTED MATTHEW DACOSTA P a g e | 1
The purpose of the experiment was to find the equation of the redox reaction with the help of
quantitative and qualitative analysis of the reaction where Bromate ions and Hydroxylammonium ions
are reacted to find the identity of the nitrogen containing product.
II. Experimental method
1. Using a burette, 20mL solution of KBrO was 3easured and transferred into a 250mL
2. A 10mL of NH OHCL3solution was measured using a volumetric pipette and delivered it into
the Erlenmeyer flask.
3. Then, with a graduated cylinder, 15mL of Hydrochloric acid was introduced into the mixture
and the flask was kept under a fume hood to ensure any gas that evolved during the reaction
escaped through the fume hood.
4. The mixture was mixed thoroughly by swirling and the flask and was allowed to rest under the
fume hood with a watch glass covering the opening of the flask.
5. During the resting period, close observations were made with regards to color and temperature
changes, any evidence of gas formation etc.
6. While the mixture was resting under the fume hood, a burette was taken and rinsed with
sodium thiosulfate solution. Then, it was filled with the stock solution and the initial reading
of the burette was noted.
7. After 10 minutes of reaction period, the flask was removed from the fume hood and 5mL of
potassium iodate solution was added to the mixture and mixed well.
8. The mixture was immediately titrated with the sodium thiosulfate solution from the burette
until the solution in the Erlenmeyer flask turned pale yellow.
9. A 2mL of starch solution was added to the flask. Since the titration was done accurately, the
solution changed into a deep blue color P a g e | 2
10. Following the color change, drop wise titration was performed to ensure that the equivalence
point was reached as accurately as possible.
11. The final reading of the burette was noted down and the volume of Na S O used to titrate was
2 2 3
calculated by calculating the difference between the initial and the final burette readings.
12. The procedure was repeated 3 times and the results were averaged to arrive at the best possible
III. Collection of Data
Refer to Data Sheet in the Appendix
IV. Results and Calculations
From conducting the experiment, the following data was obtained.
Trial # Volume of KBrO (0.3200M) Volume of Na S2O 2031003M)
Trial 1 20.00mL 12.00mL
Trial 2 20.00mL 10.60mL
Trial 3 20.00mL 10.75mL
Table 1.1 – Volume of KBrO t3trated with Na2 2O 3for more details, refer to appendix)
Number of moles of Na S O and KBrO was calculated using where ‘n’ is the number of moles
2 2 3 3
and ‘M’ is the Molarity of the given solution and ‘v’ is the volume of the given solution .
BrO + 9I + 6H O → Br + 3 I + 9H O---------- Equation ①
3 3 3 2
- - - -
[I3+ 2S 2 →33I + S O ] 4 6 -------------------- Equation ②
BrO + 6S O + 6H O → Br + 9H O + 3S O ---------- Equation ③ ( Equation ① + ②)
3 2 3 3 2 4 6
By adding Equation ① and Equation ② , the following observations were made. P a g e | 3