Iodine Clock Reaction Lab Report

0.0375 mg/ml Porcine Pancreatic Amylase Solution (amylase powder in 0.9% NaCl ), Iodine Solution; each solution were pipetted into each of the 5 test tubes with 5 ml of 1% starch. Each tube contained a 1% starch solution with a different pH. All tubes were at room temperature. Room temperature was 22C. 0.2 ml of porcine pancreatic amylase solution was then pipetted into each tube. A timer was started and every 3minutes the starch / amylase mixture were pipetted from each tube and pipetted into the spot plate for every sample tube, then the iodine solution were added to a spot plate cell for each sample. Iodine reacts with starch to change from yellow to deep blue /black in the presence of starch. A lightening of the blue/ black to a brown color will occur as less starch is present. Results were reported as (+) for presence of starch in the sample or (–) for the absence of starch. After every three minute increment had passed, these same

The iodine test is used to identify glycogen and starch. These polysaccharides combine with iodine to

The rate of reaction between Catalase and the hydrogen peroxide (H2O2) can vary depending on many factors including the enzyme concentration in a solution. In this investigation, the rate of reaction will be measured by the change in temperature of the liquefied spinach (catalase) over a period of 30 seconds, once the hydrogen peroxide (H2O2) has been added into the solution.

Introduction: First discovered by Hans Heinrich Landolt in the 19th century, the Iodine Clock reaction is what is described as a chemical clock reaction, and today is one of only few known to science. It is useful as a tool in determining the rate of a chemical reaction due to a marked change in the color of the reacting solution when a particular reaction has been completed. The process is also practical as an introduction to reaction rates and kinetics. A solution of hydrogen peroxide is mixed with one containing potassium iodide, starch and sodium thiosulfate. After a varying amount of time the colorless mixture suddenly turns dark blue which is one of a number of reactions related to the iodine clock.

Sodium Iodide is not an electrophilic source for Iodine because Iodine is the least reactive of all the halogens, and it itself does not serve as a base, due to its positive charge. This means that Sodium Iodide needs an Oxidizing agent to make it a strong electrophile.

In this experiment redox-based titrimetric analysis was used to determine the amount of ascorbic acid (Vitamin C) contained in a serving of lemonade. This was done to confirm the 100 percent recommended daily allowance claimed on the package for a serving of Country Time Lemonade. The titration method used was adding a thyodene indicator to the analyte (lemonade solution) there is a visible colour change when the endpoint of the reaction between the titrant (KIO3) and the analyte occurs. The following reactions show how this titration method is viable. (Draw in reactions) KIO3 first reduced with iodide (I-) to generate iodine (I2 ) which then oxidized the ascorbic acid within the lemonade. Once all the ascorbic acid had reacted any iodine

In order to determine when the reaction came to completion, a starch/iodine test was used. The starch/ iodine test indicates if excess reagent, sodium hypochlorite, is still present in the reaction vessel. The excess sodium hypochlorite oxidizes the iodide in the strip forming a triiodide anion. This anion then reacts with starch changing the strip to a deep blue color.

This experiment will measure the rate of oxidation of iodide ions by persulphate ions to derive the rate law for the reaction. Starch will be added to the reaction to facilitate the measure of time during the reaction. The reactant solutions will contain (NH4)2SO4 and KI, represented as:

The Iodine Test is used to identify the presence of starch or glycogen. If starch is present, the Lugol’s iodine solution will react with the solution being tested to form a dark blue or violet colour. If glycogen is present, the solution will turn a reddish-brown or brown-blue colour (Harisha, 2005, p.44). Using this test, it is possible to determine

After I collected the data the how much Iodine reacted, I averaged my measurements and used those value in calculations. This approach helped me to minimize the different errors of measurement. The concentrations of Ascorbic Acid could be calculated by referring to the values of Iodine solution as a standard. Finally, I found that Cran-apple juice has the highest concentration of Vitamin C, Green Tea has the second highest, then Rose Hips, and orange has the least concentration of Vitamin C. These results are shown in the graphs. However, the results did not support my

lets start with a brief history of the name “Iodine” . In 1811 a French Chemist (Bernard Courtois) obtained a Violet vapour by heating seaweed ashes with sulphuric acid. The vapour condensed to a black crystalline substance, which he called “Substance X”. Later, in 1813 a British Chemist (Sir Humphry Davy) recognised the so called “Substance X” and suggested that the name “Iodine” originated from the Greek word “Ioeides” meaning “violet coloured”

Each reaction would be carried out by mixing five different solutions four times separately and each reaction is consisted of KI solution, starch solution, Na2S2O3 solution, KNO3 solution and EDTA solution. The concentration of each solution varies because the first reaction include 25.0ml KI solution, 1.0ml starch solution, 1.0ml Na2S2O3 solution, 48.0ml KNO3, 1 drop EDTA solution and the total volume eqaul 75.0ml. The second reaction include 25.0 mL KI solution 1.0 mL starch solution 1.0 mL Na2S2O3 solution 23.0 mL KNO3 solution 1 drop EDTA solution and total volume equal 50.0ml. The third reaction include 50.0 mL KI solution 1.0 mL starch solution 1.0 mL Na2S2O3 solution 23.0 mL KNO3 solution 1 drop EDTA solution and the total volume equal 75.0 mL and the fouth reaction include 12.5 mL KI solution 1.0 mL starch solution 1.0 mL Na2S2O3 solution 35.5 mL KNO3 solution 1 drop EDTA solution and total volume equal 50.0ml. After obtaining all of the solutions and seven different test tubes of 1.0ml Na2S2O3 solution which should be pour into the Erlenmeyer flask whenever the color of the solution changes. To calculate the reaction rate of each reaction the timer should start immediately when all of the solutions are mixed. Once all of the solutions have been mixed the students should observe as well as record the time of the reaction when the color change to dark blue and one of

To vary the concentrations of each reactant along with the sulphuric acid in order to observe and measure its effect on the overall rate of reaction in absorbance using colourimetry.

(6.2)Material and Methods in the process or exercise of measuring the starch we were used the following material and how we used them to conduct the experiment. Obtain seven tubes the material to be tested table 6.1 and then add seven to ten drops of iodine to each tube, and then record the color of the tubes contents in table 6.1

The procedure was performed as follows: For run 1, 20cm3 of acetone, 10cm3 of sulphuric acid and 145cm3 of water was added to a conical flask. 25cm3 of iodine was then added to this solution which started the reaction and immediately, 20cm3