IA on effect of inhibitor concentration copper on enzyme catalase (yeast extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

1. Pt/Pd surface
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 Heterogenous catalyst – lower activation energy
• Homogeneous catalyst – catalyst and reactant in same phase/state
• Heterogeneous catalyst – catalyst and reactant in diff phase/state
• Heterogenous catalyst- 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
2H2O2 + Fe2+ → 2H2O+O2+Fe3+
H2O2+Fe2+→H2O + O2 + Fe3+
Fe3+ + I - → Fe2+ + I2
Fe2+ ↔ Fe3+
Rxn slow if only I- is added H2O2 + I- → I2 + H2O + O2
Rxn speed up if Fe2+/Fe3+ added
Fe2+ change to Fe3+ and is change back to Fe2+ again
recycle
molecule adsorp on
surface catalyst
Pt/Pd surface
Bond break
Bond making
3+
CH2 = CH2 + H2 → CH3 - CH3
Nickel catalyst
Without
catalyst, Ea
CH2= CH2 + H2 CH3 - CH3
Surface of catalyst for adsorption
With catalyst, Ea
adsorption
H2
adsorption
C2H4
bond breaking
making
desorption
C2H6
Fe2+ catalyst
How catalyst work ?
Activation energy
Effect of inhibitor conc Cu on enzyme catalase (yeast extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

2. Across period
Cr - 4s13d5
• half filled more stable
Cu - 4s13d10
• fully filled more stable
Ca
4s2
K
4s1
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
Effect of inhibitor conc Cu on enzyme catalase (yeast extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

3. Centrifuge to spin down the extract Catalase extract (clear solution used) Yeast, pressure sensor, H2O2
Diff conc Cu2+was used (0.001, 0.03125, 0.125, 0.25, 0.50, 1.00M).
5% (v/v) H2O2 used.
Pressure sensor to measure O2 released.
Reaction mechanism
Procedure:
5g of yeast powder added to 50ml water (10%) – centrifuge to collect catalase extract
1ml catalase extract added to 1 ml of Cu2+ solution (diff conc)
Solution added to 5ml of 5% H2O2
Rate was measured – change of pressure over time.
Hydrogen peroxide decomposition – O2 production
2H2O2→ 2H2O + O2
Effect of inhibitor conc Cu on enzyme catalase (yeast extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

4. Metal chosen as they will not act as catalyst to break down H2O2
Negative control - only Cu2+ without any catalase
Positive control – only catalase without any transition metal.
Pressure increase - due to enzyme catalase, and not transition metal.
Cu conc/M Rate/kPas-1
0.001 1.846
0.03125 0.7355
0.125 0.3819
0.250 0.3723
0.500 0.3457
1.000 0.3116
+ve control 2.199
-ve control 0.01920 Rate of decomposition decreases as conc Cu2+ increases.
Cu metal strong inhibitor for enzyme catalase
Diff Cu conc were used.
Rate measured as change of pressure over time.
0
0.5
1
1.5
2
0 0.2 0.4 0.6 0.8 1 1.2
Rate
of
decomposition
conc Cu2+
Conc Cu2+ vs Rate of decomposition
Effect of inhibitor conc Cu on enzyme catalase (yeast extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

5. Method 1 Method 2
Time Time
Volume Pressure
• Rate = Δ vol O2 over time
• Volume recorded
• Rate = Δ pressure O2 over time
• Pressure recorded
Procedure
2H2O2 → O2 + 2H2O
Rxn: H2O2 with diff (catalyst) measured using TWO diff methods
• 2H2O2 → O2 + 2H2O
(H2O2 limiting, KI excess)
• Pipette 1ml 1.0M KI to 20ml of 1.5% H2O2
• Vol O2 released recorded at 1 min interval
• Repeated using 3% H2O2 conc
Time/m Vol O2
(H2O2 1.5%)
Vol O2
(H2O2 3.0%)
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 O2
Time
3 %
1.5 %
Effect of inhibitor conc Cu on enzyme catalase (yeast extract) on the rate of decomposition of H2O2 measured using a pressure sensor.

6. • 2H2O2 → O2 + 2H2O
(H2O2 limiting, KI excess)
• Pipette 1ml 1.0M KI to 20ml of 1.5% H2O2
• Pressure O2 released recorded at 1 min interval
• Repeat using 3% H2O2 conc
Method 1 Method 2
Time Time
Volume Pressure
• Rate = Δ vol O2 over time
• Volume recorded
• Rate = Δ pressure O2 over time
• Pressure recorded
Procedure
2H2O2 → O2 + 2H2O
Time
3 %
1.5 %
Time/m Pressure O2
(H2O2 1.5%)
Pressure O2
(H2O2 3%)
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 O2
Rxn: H2O2 with diff (catalyst) measured using TWO diff methods
Effect of inhibitor conc Cu on enzyme catalase (yeast extract) on the rate of decomposition of H2O2 measured using a pressure sensor.