2. Watch the following reaction and fill in the data table provided. Sodium thiosulfate is combined with hydrochloric acid. One of the products is solid sulfur. The reaction rate can be determined by timing how long it takes for a marked X to disappear. Na 2 S 2 O 3 (aq) + HCl(aq) --> H 2 O(l) + SO 2 (g) + S 8 (s) + NaCl(aq)

3. Using the reaction between HCl and Na 2 S 2 O 3 determine a rate equation by conducting 6 trials. The first three trials leave one concentration constant while varying the other concentration by factors of 2. The 2nd 3 trials do the same thing for the other reactant. The formula for concentration change is C 2 = C 1 V 1 /V 2

5. Calculations 1. Fill in the data table and either show the formulas on a spreadsheet or write them out. 2. Show how you arrived at the rate expression. 4. Calculate the value of k 5. Compare your value of k with another group and calculate the percent difference. (difference/your value)x100

6. Graphs 1. Time (y axis) vs [HCl] (x axis) 2.Rate (y axis) vs [HCl] (x axis) 3.Time (y axis) vs [Na 2 S 2 O 3 ] (x axis) 4.Rate (y axis) vs [Na 2 S 2 O 3 ] (x axis)

7. Next Step - Affect of Temperature on Reaction Rate Design an experiment to determine the effect of temperature on the rate of this reaction. Organize your findings in a data table along with calculations. Calculations Find the rate (mol/L/s) at 5 different temperatures. Calculate k at 5 different temperatures.

8. Graphs 1. Time (y axis) vs temperature (x axis) 2.Rate (y axis) vs temperature (x axis)