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# PRE-LAB QUESTIONS

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Author: Christine Farr
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http://theperfecthomework.com/pre-lab-questions/

Pre-Lab Questions
1.     How many grams of IKI would it take to obtain a 100 mL solution of 0.300 M IKI?  How many grams of IKI would it take to create a 100 mL solution of 0.600 M IKI?
8.79 grams
17.57 grams
2.     What is the molarity of 100 mL of a 3.0% H2O2(mass/volume) solution?  100 mL of a 2.25% H2O2 solution?
0.900M
0.700M

Experiment 1: Calculating Rate of Reaction
In this experiment you will calculate the rate of reaction of potassium iodide and hydrogen peroxide. The order of the reaction will also be determined.
Materials:
20 mL 3% Hydrogen peroxide, H2O215 mL Iodine-Potassium Iodide Solution, IKI (1% Iodine, 2% Potassium Iodide)100 mL Beaker10 mL Graduated cylinder100 mL Graduated cylinder250 mL Beaker(2) 250 mL Erlenmeyer flasks1-Hole Rubber stopper2-Hole Rubber stopper(2) 3 in. Rigid tubing pieces (1) 6 in. Rigid tubing6 Pipettes

*24 in. Flexible tubing
* You must provide
*You must cut this piece of tubing into two, 12 inch pieces. (if you have not already done so).

Procedure
Preparation of Apparatus
Set up apparatus as shown in Figure 2. To do this, begin by labeling the Erlenmeyer Flasks as 1 and 2. The reaction will take place in Flask 1.
Fill Flask 2 approximately three quarters of the way full with water.
Press the 2-hole rubber stopper into the top of Flask 2. Place one three in. piece and one six in. piece of rigid tubing into each hole of the rubber stopper. This should create an airtight system.
Place the one-hole stopper on Flask 1, and fit the remaining 3 in. piece of rigid tubing in the stopper hole.
Connect Flask 1 and Flask 2 with the two, 12 in flexible tubing pieces. One piece should connect Flask 1 to Flask 2, and the second piece should connect Flask 2 to the graduated cylinder. The tubing which connects Flask 2 to the graduated cylinder should be positioned low enough to be immersed in the water in Flask 2.

Figure 2: Apparatus set-up. Note this is a sample set-up and is not drawn to scale. Your specific equipment may vary slightly.

Part A: Preparation of Reactants
Pour five mL of the IKI solution into a 10 mL graduated cylinder.
Add five mL of distilled water to the graduated cylinder to bring the total volume to 10 mL. This is the 0.5% - 1.0% (diluted) IKI solution.
Pour 15 mL of 3% H2O2 solution into a 100 mL beaker.
Add five mL of distilled water to this beaker and mix with a stir rod. This is the 2.25% (diluted) H2O2 solution.

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