Copy of Iodine Clock Lab

A Study on the Impact of Concentration Variation on Reaction Rate in an Iodine Reaction System By: Parker Tavis On June 5th, 2023 Table 1. Observations of the Change in Reaction Rate Depending on the Different Concentrations of an Iodate Solution to Distilled Water. Well number In Spot Plate Drops of Solution A (0.020mol/L) Drops of Water Time until color change (s) 1 1 9 *No change within time frame (12m) 2 2 8 502.91 3 3 7 256.25 4 4 6 127.64 5 5 5 96.08 6 6 4 82.93 7 7 3 57.96 8 8 2 54.32 9 9 1 50.35 10 10 0 36.86

Qualitative Observations: - When a well spot 10 was introduced, it resulted in the formation of a muddy brown color. As the reactions prior to that had lower concentrations of the iodate solution, the intensity of the brown color progressively decreased. Eventually, when 9 drops of water were added, there was no observable change in color. First Reaction IO 3 - (aq) + 3 HSO 3 - (aq) → 3 SO 4 2- (aq) + I - (aq) + 3H + (aq) Second Reaction 6 H + (aq) + IO 3 - (aq) + 5 I - (aq) → 3 I 2 (aq) + 3 H 2 O (l) Third Reaction I 2 (aq) + starch = blue-black complex Analyze and Evaluate a) What variables were measured/recorded and/or manipulated in this investigation? - The concentration amount of solution A - The concentration of water b) Calculate the concentration of iodate ions in each of the wells at the end of Step 2. In Step 2, the concentration remains unchanged as no water is added to the solution. However, in Step 3, when water is added, we can calculate the resulting concentration using the following formula: Calculated Concentration = (Concentration of Solution A (M)) x (Drops of Solution A) / (Total Volume) For instance, if Solution A has a concentration of 0.01 mol/L and 1 drop of it is added to a total volume of 10, the calculated concentration would be 0.01 M x 1 / 10 = 0.001 M. By repeating this step for all the concentrations of Solution A to water ratios, we can determine the resulting concentrations. Table.2 Concentration of Iodate Ions After Step 3 of the Process Well Number Concentration after step three (mol/L) 1 0.001 2 0.002 3 0.003 4 0.004

8 0.004 9 0.0045 10 0.005 d) Using tables and graphs of your observations, identify the order of the reaction with respect to the concentration of iodate ions. Table.4 The Concentration of Solution A and Solution B in Comparison to Reaction Time Well number In Spot plate Initial [A] (Solution A) (mol/L) Initial [B] (Solution A) (mol/L) [A] in [B] (mol/L) Time until color change (s) 1 0.001 0.01 0.0005 *No change within time frame (12m) 2 0.002 0.01 0.001 502.91 3 0.003 0.01 0.0015 256.25 4 0.004 0.01 0.002 127.64 5 0.005 0.01 0.0025 96.08 6 0.006 0.01 0.003 82.93 7 0.007 0.01 0.0035 57.96 8 0.008 0.01 0.004 54.32 9 0.009 0.01 0.0045 50.35 10 0.01 0.01 0.005 36.86

- - The concentration of Solution B, [Solution B], does not impact the overall rate of the reaction since it remains constant. By examining Table 4, we can identify which concentrations are increasing and observe their effect on the overall reaction time, leading to a color change. - - From Figure 1, it is evident that the order of the reaction cannot be linear since the reaction time does not decrease linearly in relation to concentration changes. - - To determine the order of the reaction, we can compare the change in concentration to the change in reaction time. Using the general equation ([Well A]/[Well B])^x = (Time B/Time A), where x represents the order of the reaction with respect to Iodate Ions, [Well A]/[Well B] indicates the concentration change relative to A, and Time B/Time A signifies the change in reaction time relative to B. - - Analyzing Wells 2-4 using this equation, we observe that the time until the reaction shortens by approximately four times when [A] + [B] is doubled. - Calculations: Plugging the numbers in from well 2-4 we get: ((0.002)/(0.001)) x = 502.91/127.69 2 x = 3.94 2 x ≈ 4 (Round here for simplicity) x ≈ ln(4)/ln(2) x ≈ 2