Iodine Clock Reaction
Iodine Clock Reaction
Lab #18
Purpose: To mix different solutions to see how increasing the concentration changes the reaction rate.
Materials:
· 250 ml beaker, a 50 ml beaker and 50 ml flask
· Graduated cylinder
· Solution B: Na2S2O5 solution with starch & 5mL of 1M H2SO4 made with 0.22g of Na2S2O5 and 4g of starch in 1L deionized H2O. (Note add the H2SO4 day of the lab.)
· Solution A: KIO3 solution made with 4.4g KIO3 dissolved in 0.6L of deionized H2O.
· Catalyst solution: Ammonium molybdate (VI) tetrahydrate 0.176g per 100mL of water
Procedure:
1. Clean 250 ml beaker, a 50 ml beaker and 50 ml flask.
2. Fill a 250 ml beaker with deionized water.
3. Trial #1: Add 2 ml solution A and 8 ml deionized H2O to a flask. Add 10 ml of solution B to a separate beaker. Mix the solutions in the flask and record the time in seconds until the color changes.
4. Trial #2: Add 4 ml solution A and 6 ml deionized H2O to a flask. Add 10 ml of solution B to a separate beaker. Mix the solutions in the flask and record the time in seconds until the color changes.
5. Trial #3: Add 6 ml solution A and 4 ml deionized H2O to a flask. Add 10 ml of solution B to a separate beaker. Mix the solutions in the flask and record the time in seconds until the color changes.
6. Trial #4: Add 8 ml solution A and 2 ml deionized H2O to a flask. Add 10 ml of solution B to a separate beaker. Mix the solutions in the flask and record the time in seconds until the color changes.
7. Trial #5: Add 10 ml solution A to a flask. Add 10 ml of solution B to a separate beaker. Mix the solutions in the flask and record the time in seconds until the color changes.
8. Trial #6: Testing a catalyst. Add 2.0 ml of solution A, 0.5 ml of Catalyst, and 7.5 ml deionized H2O to a flask. Add 10 ml of solution B to a separate beaker. Mix the solutions in the flask and record the time in seconds until the color changes
Data: Trial Time (sec)
Trial #1
Trial #2
Trial #3
Trial #4
Trial #5
Trial #6
Analysis:
Show the calculations for how you would calculate the molarities KIO3 and Na2S2O5 stock solutions?
Calculate the molarity of Solution A in trials 1-5.
Plot the Molarity of solution A versus time for solution A for trial 1-5. This graph will have 5 points. Plot concentration on the y-axis and time on the x-axis. (Graph should be 1/2 page).
Conclusion:
Does the plot make a straight line? What does a catalyst do for the reaction? How did the concentration of solution A control the rate?