Catalyst and Catalytic Effect 2020/09/16 Prepare Collect Test - - PowerPoint PPT Presentation

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Catalyst and Catalytic Effect 2020/09/16 Prepare Collect Test - - PowerPoint PPT Presentation

Jan 17, 2023 317 likes •484 views

Catalyst and Catalytic Effect 2020/09/16 Prepare Collect Test tubes (wash and dip dry) Plastic basin Test tube rack Watch glass Tweezers 50 mL graduated 50 mL graduated cylinder cylinders (2) 100 mL beaker

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SLIDE 1

1

Catalyst and Catalytic Effect

Collect

◼ Plastic basin ◼ Watch glass ◼ 50 mL graduated

cylinders (2)

◼ Plastic droppers (2) ◼ Cotton gloves ◼ Timer (by TA)

（2020/09/16）

Prepare

◼ Test tubes (wash and dip dry) ◼ Test tube rack ◼ Tweezers ◼ 50 mL graduated cylinder ◼ 100 mL beaker

Share

◼ Knife and scissors ◼ Evaporating dish ◼ carton box ◼ Spray ◼ Incense and match (in hood)

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SLIDE 2

2

Objective

◼

Decomposition of hydrogen peroxide

◼

Chemiluminescence of luminol

◼

Catalytic effect of catalyst

Techniques

◼

Weighing

◼

Magnetic stirrer and hot plate

◼

Graduated cylinder and dispenser

◼

Liquid nitrogen

Objective & Techniques

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SLIDE 3

3

  • I. Decomposition of Hydrogen

Peroxide

2 H2O2(aq)

Catalyst

O2(g) + 2 H2O(l)

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SLIDE 4

發光胺

NH2 O O NH NH + 2OH- + 2H2O2

Iron ions

+ 4H2O + N2 基態

hν

O

  • O
  • O

O N H2

4

  • II. Chemiluminescence of

Luminol

*

Luminol Ground state

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SLIDE 5

Catalytic Effect of Catalyst

▪ Catalyst

A catalyst is a substance which increases the rate of a chemical reaction

▪ Types

– Homogeneous catalyst – Heterogeneous catalyst – Biocatalyst (enzyme)

▪ Mechanism?

5

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SLIDE 6

6

Enzyme

◼ Enzyme: a biocatalyst ◼ Characteristics

–High specificity –High efficiency –Activity affected by pH, temperature… etc. ▪ Why?

▪ Protein: a polymer of amino acids ▪ Possess specific function for special structure

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SLIDE 7

7

Experimental Flowchart

  • I. Decomposition of H2O2

by catalyst – MnO2(s) – KI(aq) – Pig liver

  • Fresh
  • Frozen
  • Boiled

–Blood from pig liver

  • II. H2O2 and luminol

– Pig liver blood – K3[Fe(CN)6] – K4[Fe(CN)6]

  • III. Forensic chemistry

– Detection of blood

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SLIDE 8

Step I. MnO2 and H2O2

  • Weigh 0.1 g MnO2

and add 3 d dishwashing liquid into 50 mL graduated cylinder

8

  • Add 5 mL H2O2 soln
  • Mix well
  • Record rxn time and

volume of bubbles formed

  • Insert burning

incense into gas bubbles

  • Inspect the property
  • f gas evolved
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SLIDE 9

Step II. KI Solution and H2O2

Add 1 mL 2.0 M KI(aq) and 3 d dishwashing liquid To 50 mL graduated cylinder Add 5 mL 10 mL 2%H2O2 Mix well Record rxn time and volume Test with burning incense

9

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SLIDE 10

▪ Take 3 pieces of 50 mL graduated cylinder ▪ Add 3 d dishwashing liquid and 1) Fresh pig liver 2) Frozen pig liver 3) Boiled pig liver 4) Blood from pig liver

10

Record: Rxn time & bubble volumes Cut to slices Freeze pig liver in liquid nitrogen

5 mL of 3%H2O2

Step III. Pig Liver and H2O2

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SLIDE 11

Step IV. Luminol and H2O2

Take 5 test tubes, each filled with (1) 1 mL H2O & 2 d. blood from pig liver (2) 1 mL 0.2 M K3Fe(CN) 6 (3) 1 mL 0.2 M K4Fe(CN)6 (4) 1 mL H2O & 1 d. K3Fe(CN) 6 (5) 1 mL H2O & 5 d. K3Fe(CN) 6 Use a test tube to take 3 mL luminol test soln Add 0.5 mL of luminol test soln to #(1)~(5)

  • ne by one

Observe and record chemiluminescence Add more Fe(III) to tubes (4) and (5)

11

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SLIDE 12

Step V. Luminol and Forensic

Collect the luminol test soln left in a spray

12

Spray the luminol test soln

  • n to tissue, knife, or

scissors used Take the picture for recording

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SLIDE 13

13

Summary I

3 d dishwashing liquid + 5 mL 3%H2O2 Catalyst 0.1 g MnO2(s) 1 mL KI(aq)

Fresh pig liver Frozen pig liver Boiled pig liver 2 d Blood from pig liver

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SLIDE 14

14

Summary II

Test tube Reagent 1 mL H2O2 + 2 d. pig liver blood 0.5 mL Luminol test soln 1 mL 0.2 M K3Fe(CN) 6 + 1 mL 0.2 M K4Fe(CN)6 1 mL H2O & 1 d. K3Fe(CN) 6 1 mL H2O & 5 d. K3Fe(CN) 6

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SLIDE 15

15

Notice

◼ Start counting time while H2O2(aq) being added to

the reacting solution

◼ Take and place burning incense back into fume

hood to avoid smoke accumulating in lab.

◼ Wear cotton gloves to avoid burned by hot plate or

boiling water

◼ Be cautious of operating with liquid nitrogen for low

temperture

◼ Recycle the plastic droppers after used ◼ Boil all the pig liver after use and recycle ◼ Give the timer back to TA ◼ Clean the apparatus, lab bench after class

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SLIDE 16

16

Dispenser

  • 1. Check the pre-set volume and

do not change the volume setting afterwards.

  • 2. Position the flask under the tip
  • f dispenser.
  • 3. Lightly pull the piston pump up

and down several times to get rid of the bubbles.

  • 4. Lightly pull piston pump up to

the top, then slowly push down to obtain the measured solution.

（2） （1） （3） （4）