Part A: Determination of Overall Reaction Order 1. Calculate the initial concentration of each of the two major reactants in each of the reaction mixtures, V through Z, detailed on Table 1. Enter all the concentration values in Table 3. Show a sample calculation for mixture V. Note: The concentration of the species in the reaction mixture will not equal the concentration of the species in the stock solution. 2. Calculate the average time taken for mixtures V through Z. Show a sample calculation for mixture V. 3. Calculate the reaction rate (A[12]/At) for mixtures V through Z. Show a sample calculation for mixture V. (Hint: check your Prelab calculations.) 4. Calculate the reaction order with respect to iodide ion, n, by observing the change in the rate of the reaction as the iodide ion concentration in the reaction mixture was changed (i.e. compare the rates in V to Y, Y to Z, and V to Z). Calculate a mean value for n, and report its value to the nearest integer. Enter the values in Table 4. Show a sample calculation for comparing mixtures V and Y. Similarly, calculate the reaction order with respect to persulphate ion, m (i.e. compare the rates in V to W, W to X, and V to X). Calculate a mean value for m and report its value to the nearest integer. Express the rate law in the form: Rate = k[11"[S2082-1 5. Calculate the specific rate constant, k, for each of the acceptable trials for mixtures V through Z. Show a sample calculation for one trial of mixture V. Enter the values of k in your Table 5 and calculate a mean. Part B: Determination of Activation Energy 6. Calculate the specific rate constants for each of the acceptable trials measured in the ice-water bath and the warm water bath. Show a sample calculation for the determination of k, using the data from one acceptable trial in the ice-water bath. Enter the values of k, T(C), and of T(K) for each of the acceptable trials in the ice bath, at room temperature, and in the warm water bath in Table 6. (The values of k at room temperature were determined in Part A above.) Calculate in k and T-1. Enter the values in the Table. Plot a graph of In k vs T, including each acceptable trial in the ice water, room temperature, and warm water baths. Draw the best straight line fit using these data points. Calculate the slope of the plot line, and from the slope the value of the activation energy (Ea) for Reaction (1). Show your calculations on the graph paper. Part C: Effect of a Catalyst on Reaction Rate 7. Calculate the rate for one of the acceptable trials in the reaction catalyzed by copper(ll) ion. What effect did the addition of copper(II) sulphate have on the rate of Reaction (1)? (Hint: catalyst effect = rate with catalyst / rate without catalyst) RESULTS Table 3: Determination of Reaction Rates V W Y Z [S2O82-1 Ul (mol L"") (mol L ) (s) average time rate (mol Ls-) Sample calculation for mixture V: 1. a) [S2082-) = b) [1] = 2. average time = 3. rate = A[12] t Table 4: Determination of Reaction Order Comparison n V to W V to X V to Y V to Z W to X Y to Z (integer) (integer) mean Rate law: Rate = k [l'1? [S2O82-1? -34- 4. Sample calculation for comparing mixtures V and Y: = rate V = [l] / rate Y n = Table 5: Determination of Specific Rate Constant V W Y Z k (L molts!) k, mean (V to Z) 5. Sample calculation of "k" for mixture V: L mol s1 a) k= b) k, mean of trials of mixtures V to Z: Table 6: Determination of Activation Energy Mixture V Cold water Room temp. Hot water Tr#1 Tr#2 Tr#3 Tr#1 Tr#2 Tr#1 Tr#2 Tr#3 (S2082:(mol L-") (mol L-1) Time (At) (s) rate (mol L 51) k (L molt s=1) In k T (C) T (K) (K-1) T-1 6. Sample calculation for Cold Water, Trial #1 : rate = k= 7. rate (without catalyst) = rate (with catalyst) effect = DATA Table 2 Trial 1 Tria Mix Ti Time (s) TI (C) Time (s) (C) V 139.0 22.1 22.3 W 181.0 21.8 22.0 160.6 22.0228 Y 1766 22.0 22.2 N 131.4 235 23.5 23.5 Cold V 208.41.0 12.0 Hot V 18.1 320 132-3 323 Catal- yzed 1.4 21.0 21:3 V Table 1: Volume of reactants Compound Reaction Mixtures (mL) V w Y N 20.00 10.00 ammonium persulphate 5.00 20.00 20.00 20.00 20.00 20.00 10.00 5.00 10.00 0.00 15.00 0.00 0.00 potassium iodide ammonium sulphate potassium chloride sodium thiosulphate 0.00 0.00 0.00 10.00 15.00 10.00 10.00 10.00 10.00 10.00 Part A: Determination of Overall Reaction Order 1. Calculate the initial concentration of each of the two major reactants in each of the reaction mixtures, V through Z, detailed on Table 1. Enter all the concentration values in Table 3. Show a sample calculation for mixture V. Note: The concentration of the species in the reaction mixture will not equal the concentration of the species in the stock solution. 2. Calculate the average time taken for mixtures V through Z. Show a sample calculation for mixture V. 3. Calculate the reaction rate (A[12]/At) for mixtures V through Z. Show a sample calculation for mixture V. (Hint: check your Prelab calculations.) 4. Calculate the reaction order with respect to iodide ion, n, by observing the change in the rate of the reaction as the iodide ion concentration in the reaction mixture was changed (i.e. compare the rates in V to Y, Y to Z, and V to Z). Calculate a mean value for n, and report its value to the nearest integer. Enter the values in Table 4. Show a sample calculation for comparing mixtures V and Y. Similarly, calculate the reaction order with respect to persulphate ion, m (i.e. compare the rates in V to W, W to X, and V to X). Calculate a mean value for m and report its value to the nearest integer. Express the rate law in the form: Rate = k[11"[S2082-1 5. Calculate the specific rate constant, k, for each of the acceptable trials for mixtures V through Z. Show a sample calculation for one trial of mixture V. Enter the values of k in your Table 5 and calculate a mean. Part B: Determination of Activation Energy 6. Calculate the specific rate constants for each of the acceptable trials measured in the ice-water bath and the warm water bath. Show a sample calculation for the determination of k, using the data from one acceptable trial in the ice-water bath. Enter the values of k, T(C), and of T(K) for each of the acceptable trials in the ice bath, at room temperature, and in the warm water bath in Table 6. (The values of k at room temperature were determined in Part A above.) Calculate in k and T-1. Enter the values in the Table. Plot a graph of In k vs T, including each acceptable trial in the ice water, room temperature, and warm water baths. Draw the best straight line fit using these data points. Calculate the slope of the plot line, and from the slope the value of the activation energy (Ea) for Reaction (1). Show your calculations on the graph paper. Part C: Effect of a Catalyst on Reaction Rate 7. Calculate the rate for one of the acceptable trials in the reaction catalyzed by copper(ll) ion. What effect did the addition of copper(II) sulphate have on the rate of Reaction (1)? (Hint: catalyst effect = rate with catalyst / rate without catalyst) RESULTS Table 3: Determination of Reaction Rates V W Y Z [S2O82-1 Ul (mol L"") (mol L ) (s) average time rate (mol Ls-) Sample calculation for mixture V: 1. a) [S2082-) = b) [1] = 2. average time = 3. rate = A[12] t Table 4: Determination of Reaction Order Comparison n V to W V to X V to Y V to Z W to X Y to Z (integer) (integer) mean Rate law: Rate = k [l'1? [S2O82-1? -34- 4. Sample calculation for comparing mixtures V and Y: = rate V = [l] / rate Y n = Table 5: Determination of Specific Rate Constant V W Y Z k (L molts!) k, mean (V to Z) 5. Sample calculation of "k" for mixture V: L mol s1 a) k= b) k, mean of trials of mixtures V to Z: Table 6: Determination of Activation Energy Mixture V Cold water Room temp. Hot water Tr#1 Tr#2 Tr#3 Tr#1 Tr#2 Tr#1 Tr#2 Tr#3 (S2082:(mol L-") (mol L-1) Time (At) (s) rate (mol L 51) k (L molt s=1) In k T (C) T (K) (K-1) T-1 6. Sample calculation for Cold Water, Trial #1 : rate = k= 7. rate (without catalyst) = rate (with catalyst) effect = DATA Table 2 Trial 1 Tria Mix Ti Time (s) TI (C) Time (s) (C) V 139.0 22.1 22.3 W 181.0 21.8 22.0 160.6 22.0228 Y 1766 22.0 22.2 N 131.4 235 23.5 23.5 Cold V 208.41.0 12.0 Hot V 18.1 320 132-3 323 Catal- yzed 1.4 21.0 21:3 V Table 1: Volume of reactants Compound Reaction Mixtures (mL) V w Y N 20.00 10.00 ammonium persulphate 5.00 20.00 20.00 20.00 20.00 20.00 10.00 5.00 10.00 0.00 15.00 0.00 0.00 potassium iodide ammonium sulphate potassium chloride sodium thiosulphate 0.00 0.00 0.00 10.00 15.00 10.00 10.00 10.00 10.00 10.00