IA on effectiveness of different types of catalysts MnO2 vs Fe(NO3)3 on the rate of decomposition of H2O2 measured using a pressure sensor.

IA on effectiveness of different types of catalysts MnO2 vs Fe(NO3)3 on the rate of decomposition of H2O2 measured using a pressure sensor.

1. Pt/Pdsurface
Catalytic Properties of Transition metal
•Variable oxidation state -lose and gain electron easily.
•Use 3d and 4s electrons to form weak bond.
•Act as Homogeneous or Heterogenouscatalyst –lower activation energy
•Homogeneous catalyst –catalyst and reactant in same phase/state
•Heterogeneous catalyst –catalyst and reactant in diff phase/state
•Heterogenouscatalyst-Metal surface provide active site (lower Ea )
•Surface catalyst bring molecule together (close contact) -bond breaking/making easier
Transition metal as catalyst with diff oxidation states
2H
2O
2+ Fe
2+
→2H
2O+O
2+Fe
3+
H
2O
2+Fe
2+
→H
2O + O
2+ Fe
3+
Fe
3+
+ I
-
→Fe
2+
+ I
2
Fe
2+
↔Fe
3+
Rxnslow if only I
-
is added H
2O
2+ I
-
→I
2+ H
2O + O
2
Rxnspeed up if Fe
2+/
Fe
3+
added
Fe
2+
change to Fe
3+
and is change back to Fe
2+
again
recycle
molecule adsorpon
surface catalyst
Pt/Pdsurface
Bond break
Bond making
3+
CH
2 = CH
2+ H
2→CH
3 -CH
3
Nickel catalyst
Without
catalyst, E
a
CH
2= CH
2+ H
2 CH
3 -CH
3
Surface of catalyst for adsorption
With catalyst, E
a
adsorption
H
2
adsorption
C
2H
4
bond breaking
making
desorption
C
2H
6
Fe
2+
catalyst
How catalyst work ?
Activation energy
Comparing MnO
2vs Fe(NO
3)
3on the rate of decomposition of H
2O
2measured using a pressure sensor.

2. Across period
Cr -4s
1
3d
5
•half filled more stable
Cu -4s
1
3d
10
•fully filled more stable
Ca
4s
2
K
4s
1
Transition metal have partially fill 3d orbital
•3d and 4s electron can be lost easily
•electron fill from 4s first then 3d
•electron lost from 4s first then 3d
•3d and 4s energy level close together (similar in energy)
Filling electron-4s level lower, fill first Losing electron-4s higher, lose first
3d
4s
Comparing MnO
2vs Fe(NO
3)
3on the rate of decomposition of H
2O
2measured using a pressure sensor.

3. Solid vs solution catalyst will be compared. Assuming same surface area
Fe
3+
solution and MnO
2solid
Same amount were used –0.00005mol
5% H
2O
2used. Pressure sensor to measure O
2released.
Diff temp used to find E
a
Reaction mechanism
Procedure:
0.00005mol of each catalyst added to H
2O
2
H
2O
2and Fe(NO
3)
3solution immersed in water bath at various temp.
Diff temp used (17, 30, 35, 38, 42C)
Mass of MnO
2is 0.00435g –(0.00005mol)
Ex: 1g of Fe(NO
3)
3added to 100ml water –concis = 0.0247M
To transfer 0.00005mol Fe
3+
to H
2O
2, the volneeded will be 2ml
2ml Fe(NO
3)
3 was added to 1ml 5% H
2O
2in a boiling tube
Pressure sensor attached.
1.Comparing homogenous solution (diff transition metal) against solid MnO
2
2.Which transition metal works best (same amtof catalyst added, 0.0005mol)
3.Measure E
avalue for diff transition metal and compared to MnO
2which is 41kJmol
-1
4. Will E
ahigher/lower for heterogenouscatalyst (MnO
2) compared to homogenous catalyst
like CuSO
4, FeSO
4, FeCI
3
Research Questions
Hydrogen peroxide decomposition –O
2 production
2H
2O
2→2H
2O + O
2
Fe
3+
and MnO
2
Comparing MnO
2vs Fe(NO
3)
3on the rate of decomposition of H
2O
2measured using a pressure sensor.

4. Exptdone at diff temp for Fe(NO
3)
3
Slope/gradient taken over 15s
Rate decomposition increases exponential with temp.
Temp/
C
Temp/
K
Rate
kPa/s
1/T k lnk
17 290 0.060740.003440.06074-2.801
30 303 0.54230.003300.5423 -0.611
35 308 1.2770.00324 1.2770.2445
38 311 1.505 0.00321 1.505 0.409
42 315 2.588 0.00317 2.588 0.951
Assuming rate constant, k. = Rate of decomposition.
y = 0.0051e
0.1518x
R² = 0.989
0
0.5
1
1.5
2
2.5
3
3.5
0 10 20 30 40 50
Rate decomposition
temp/C
Rate decomposition vs temp/C
Comparing MnO
2vs Fe(NO
3)
3on the rate of decomposition of H
2O
2measured using a pressure sensor.
Fe(NO
3)
3catalyst at diff temp

5. Temp/
C
Temp/
K
Rate
kPa/s
1/T k lnk
17 290 0.060740.003440.06074-2.801
30 303 0.54230.003300.5423 -0.611
35 308 1.2770.00324 1.2770.2445
38 311 1.505 0.00321 1.505 0.409
42 315 2.588 0.00317 2.588 0.951
Arrhenius Eqn
E
afrom its gradient
Arrhenius Eqn-E
aby graphical MethodRT
E
a
eAk

.. 






TR
E
Ak
a1
lnln
Plot ln k vs 1/T
ln both sides
-E
a/R
Gradient = -E
a/R
Gradient = -13953
-13953 = -E
a/R
E
a= 13953 x 8.314
= 116 kJmol
-1
ln k
1/T
Arrhenius plot to find E
afor Fe(NO
3)
3
y = -13953x + 45.294
R² = 0.9913
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
0.003150.00320.003250.00330.003350.00340.003450.0035
lnk
1/T
lnk vs 1/T
Assuming rate constant, k. = Rate of decomposition.

6. Exptdone at diff temp for MnO
2
Slope/gradient taken over 15s
MnO
2catalyst at diff temp.
Rate decomposition increases exponential with temp.
Temp/
C
Temp/
K
Rate
kPa/s
1/T k lnk
17 290 0.40980.003440.4098-0.892
30 303 0.74660.003300.7466-0.2922
35 308 0.82740.003240.8274-0.1894
38 311 1.353 0.00321 1.3530.3023
42 315 1.445 0.00317 1.445 0.368
Assuming rate constant, k. = Rate of decomposition.
y = 0.1644e
0.0514x
R² = 0.9426
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 10 20 30 40 50
Rate decomposition
temp/C
Rate decomposition vs temp/C
Comparing MnO
2vs Fe(NO
3)
3on the rate of decomposition of H
2O
2measured using a pressure sensor.

7. Arrhenius Eqn
E
afrom its gradient
Arrhenius Eqn-E
aby graphical MethodRT
E
a
eAk

.. 






TR
E
Ak
a1
lnln
Plot ln k vs 1/T
ln both sides
-E
a/R
Gradient = -E
a/R
Gradient = -4703
-4703 = -E
a/R
E
a= 4703 x 8.314
= 39 kJmol
-1
ln k
1/T
Arrhenius plot to find E
afor MnO
2
Temp/
C
Temp/
K
Rate
kPa/s
1/T k lnk
17 290 0.40980.003440.4098-0.892
30 303 0.74660.003300.7466-0.2922
35 308 0.82740.003240.8274-0.1894
38 311 1.353 0.00321 1.3530.3023
42 315 1.445 0.00317 1.445 0.368
y = -4703.1x + 15.248
R² = 0.9375
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.003150.00320.003250.00330.003350.00340.003450.0035
lnk
1/T
lnk vs 1/T
Assuming rate constant, k. = Rate of decomposition.
0
20
40
60
80
100
120
140
Fe(NO3)3 MnO2
Activation energy
Type of catalyst
Type of catalyst vs activation energy
Comparison between solid catalyst (MnO
2) vs solution (FeNO
3)
3
Lit value E
a.forMnO
2= (41 kJmol
-1
).
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MnO
2 system has a lower E
acompared to Fe(NO
3)
3system.

8. Method 1 Method 2
Time Time
Volume Pressure
•Rate = ΔvolO
2over time
•Volume recorded
•Rate = Δpressure O
2over time
•Pressure recorded
Procedure
2H
2O
2 →O
2+ 2H
2O
Rxn: H
2O
2with diff (catalyst) measured using TWO diff methods
•2H
2O
2 →O
2+ 2H
2O
(H
2O
2 limiting, KI excess)
•Pipette 1ml 1.0M KI to 20ml of 1.5% H
2O
2
•Vol O
2released recorded at 1 min interval
•Repeated using 3% H
2O
2 conc
Time/m VolO
2
(H
2O
21.5%)
Vol O
2
(H
2O
23.0%)
0 0.0 0.0
1 8.5 14.0
2 15.0 26.5
3 21.0 34.0
4 26.0 39.0
Volume O
2
Time
3 %
1.5 %
Comparing MnO
2vs Fe(NO
3)
3on the rate of decomposition of H
2O
2measured using a pressure sensor.

9. •2H
2O
2 →O
2+ 2H
2O
(H
2O
2 limiting, KI excess)
•Pipette 1ml 1.0M KI to 20ml of 1.5% H
2O
2
•Pressure O
2released recorded at 1 min interval
•Repeat using 3% H
2O
2 conc
Method 1 Method 2
Time Time
Volume Pressure
•Rate = ΔvolO
2over time
•Volume recorded
•Rate = Δpressure O
2over time
•Pressure recorded
Procedure
2H
2O
2 →O
2+ 2H
2O
Time
3 %
1.5 %
Time/m Pressure O
2
(H
2O
21.5%)
Pressure O
2
(H
2O
23%)
0 101.3 101.3
1 102.4 103.4
2 103.5 105.6
3 110.3 115.2
4 113.5 118.2
Pressure O
2
Comparing MnO
2vs Fe(NO
3)
3on the rate of decomposition of H
2O
2measured using a pressure sensor.