This document summarizes an experiment to determine the enthalpy of decomposition of hydrogen peroxide in aqueous solution. The experiment involves first calibrating an isobaric calorimeter to determine its heat capacity. Then hydrogen peroxide solution is added to the calorimeter and manganese dioxide is used to catalyze the decomposition reaction. Temperature readings are taken before and after the reaction to determine the temperature change. The concentration of hydrogen peroxide is determined by titration and used to calculate moles reacted. From this, the enthalpy of decomposition is calculated to be -96 kJ/mole.

1. To Determine the
Enthalpy of H2O2
Decomposition in
Aqueous Solution
Presented by :-
Rajan Baa
Soumyadipa Das
Abison Scaria

2. What is calorimetry?
The process of measuring the heat of chemical reactions or physical reactions
as well as heat capacity.
Differential scanning
calorimeter
Bomb
calorimeter
Isothermal titration calorimeter
And that’s where we need a calorimeter.
Some of them are

3. We would need some pre requisite knowledge of a few
terms.
Enthalpy
Adiabatic process
Heat capacity

4. q= Cp T
H= Cp T

5. H2O2 (aq) H2O (l) + ½ O2 (g)

6. Isobaric calorimeter with stirrer and precision thermometer
100 mL volumetric flask
250 mL measuring cylinder
10 mL pipette
Chronometer
Pipette filler
Wash bottle
Spatula
Equipments:
Chemicals:
Sodium nitrite NaNO2
Sulphamic acid NH2SO3H
11.2 volume strength of H2O2
Manganese dioxide MnO2

7. Experiment
Calibration:
Measurement of
the Heat Capacity
of the Calorimeter
Measurement of
the Enthalpy of
Decomposition
of Hydrogen
Peroxide

8. Calibration: Measurement of the Heat Capacity
of the Calorimeter
NH2SO3H (aq) + NaNO2 (aq) N2 (g) + H2O (l) + NaHSO4 (aq)
For this reaction at 25 °C, rHm = –420.5 kJ mol–1
1.
Accurately weigh out 11.30 g of NaNO2, dissolve in distilled water and make
up to 100 mL in a 100 mL volumetric flask.

9. 2. Transfer 600 mL of distilled water to the calorimeter
Add 5 g of
sulphamic acid and
turn on the stirrer!

10. Switch on the stirrer and allow ten
minutes for the sulphamic acid to
dissolve completely and for an
equilibrium rate of temperature rise
to be established.
Start the chronometer and take
temperature readings at one minute
intervals for five minutes to define
the slope of the pre-reaction period.

11. On five minutes, pipette 10 mL of the NaNO2
solution into the calorimeter through the open
glass tube in the lid.

12. The temperature rises rapidly. By six minutes the actual reaction
should be complete. Continue taking readings at one minute
intervals from six minutes to ten minutes to
establish the slope of the post-reaction period.
H = Cp T
Known from literature
From the graph of temp vs time.

13. Determination of Enthalpy of decomposition of H2O2
H2O2 (aq) H2O (l) + ½ O2 (g)
H2O2
Transfer 600 mL of distilled
water to the calorimeter and
put the lid on. Attach the
stirrer cable.
Pipette 10 mL of the hydrogen
peroxide solution into the
calorimeter.

14. Switch on the stirrer and allow ten minutes for
an equilibrium rate of temperature rise to be
established.
Time
temperature

15. Weigh out roughly 6 g of manganese dioxide
On five minutes, add the manganese dioxide through the open glass
tube in the lid to catalyse the decomposition. The temperature rises
rapidly. By six minutes the actual reaction should be complete.
Time
temperature
MnO2

16. Continue taking readings at one minute intervals from six
minutes to ten minutes to establish the slope of the post-
reaction period.
temperature
time

17. time
Tf
Ti
temperature
T

18.  the concentration of H2O2 was determined by
titration against standard potassium permanganate
solution
 Given this concentration,
we can calculate the quantity of H2O2 added to the
calorimeter in moles. From the number of moles of
H2O2 added to the calorimeter, rHm was found out
to be -96 kJ /mole.

19. References:
article from manchester university press
www.chem.tamu.edu

20. Thank you...