AP Biology, Chapter 2				           Safety Level: Highest (goggles + aprons)
The Chemical Context of Life
Lab Activity: Determination of H2O2 by KMnO4 Titration

Objectives
1) Practice the quantification of H2O2 in preparation for AP Biology Lab #2, Enzyme Catalysis. 
2) Observe and manipulate a well-characterized chemical reaction.
2) Review calculations of molarity in the context of a chemical equation.

Introduction
Potassium permanganate (KMnO4), in the presence of H2O2 and H2SO4 reacts as follows:
	
	5 H2O2 + 2 KMnO4 +4 H2SO4  K2SO4 + 2 MnSO4 + 8 H2O +5 O2 

KMnO4 is pink/purple/brown. All of the products are colorless. We will be titrating with KMnO4 adding it drop-by-drop. As long as there is any H2O2 still present the color will disappear as the KMnO4 reacts. When all of the H2O2 is used up the color will remain and we stop adding KMnO4.
The total amount of KMnO4 of known molarity added allows calculation of the molarity of H2O2 in the original solution. 

General Procedure
1)	Don goggles and aprons.
2)	Obtain aging H2O2 solution, distilled water, and fresh H2O2 solution in labeled plastic cups. Also, obtain approximately 50 mL of  1 M H2SO4 (handle with care).
3)	Into a separate, clean cup or beaker deliver 10 mL of solution to be tested and 10mL of 1 M H2SO4. This simulates the reaction mix for the enzyme lab and provides the H2SO4 for the reaction.
4)	Dispense 5 mL of this mixture into the "titration" cup. 
5)	Carefully fill your burette about half full with 0.13 M KMnO4. Record the initial volume in the burette to within 0.1 mL. Place the cup containing the sample over a white sheet of paper.
6)	Add KMnO4, a drop at a time, with gently swirling. Stop adding when a persistent pink/purple/brown color is obtained. Record the final volume in the burette to within 0.1 mL.
 7)	Repeat steps 3) through 6) for each solution to be tested.

Data
Unknown H2O2 ID: ______________________________________
Fresh H2O2 ID: ______________________________________

Burette vol.
(in mL)	Water
(= Negative Control)	Fresh H2O2 (= Positive Control)	Unknown H2O2
(= Experi- mental)	Unknown
Repeat	Unknown
Repeat	
Final volume						
Initial volume						
Final - Initial						
 
Calculations
Calculate the molarity of H2O2 in the original samples. Show all calculations on the back of this sheet. Take the average for the three titrations of the unknown.