Determination of Rate Law Essay

Abstraction: A solution incorporating K iodide was assorted with a H peroxide solution to find the rate jurisprudence for the reaction between H peroxide and K iodide at room temperature and the activation energy. Ea. of the above reaction. Potassium iodide and H peroxide react harmonizing to the undermentioned equation: We found the experimental rate jurisprudence for this reaction to be and the activation energy of the reaction was calculated to be and the Arrhenius pre-exponential factor ( A ) of. Introduction All chemical reactions require some minimal sum of energy to transform the reactants into merchandises.

The rate of the reaction is the rate at which the merchandises are formed from reactants. At changeless temperature. the rate of a chemical reaction is changeless and can be determined by experimentation utilizing the general rate jurisprudence. Changing the temperature at which a peculiar reaction takes topographic point changes the activation energy of the reaction at the different temperatures. Using a transformed version of the Arrhenius equation the value of for the reaction and the Arrhenius pre-exponential factor can be determined diagrammatically. Methods There were two solutions involved in this experiment: Solution A comprised of 5.

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OmL buffer ( to stabilise [ H+ ] ) . 0. 3M KI ( a beginning of I- ) . amylum ( index for I2 ) . 0. 02M Na thiosulfate ( beginning of thiosulfate ion ) . and distilled H2O ( to convey the entire volume to 40. 00mL ) . while solution B contained 0. 1M H peroxide. In the first portion of the experiment. we determined the rate jurisprudence as follows: We prepared solutions A and B for each test utilizing the recommended volumes in Table 2 of the lab manual.

After fixing the solutions. we used separate thermometers to enter the temperature of each solution to the nearest 0. 1. guaranting that both solution temperatures did non divert by more than 0. 5. The information obtained was recorded as Table 1. After entering the temperatures. my spouse started the timer on her phone while I poured solution B into the flask incorporating solution A. The terminal of the reaction was signaled by the formation of a bluish iodine-starch composite in the flask. The sum of I produced was calculated utilizing the sum of thiosulfate ( restricting reagent in the thiosulfate-iodine reaction ) in the solution.

After executing all five tests. the values obtained for the first three tests were used to make Table 1a below. These values were so plotted utilizing Graphic Analysis and curve fitted to find the order of the reaction with regard to iodide as shown on Figure 1a. Table 1b was besides created utilizing the values for the last three tests. so plotted on a graph ( as shown on Figure 1b ) to find the order of the reaction with regard to hydrogen peroxide and two values for the rate invariable. .

The values for P and Q were rounded to the nearest whole number and the norm of the two values was so calculated to be ensuing in the rate jurisprudence for the of In the 2nd portion of the experiment. we determined the activation energy for the decomposition of H peroxide utilizing K iodide by executing tallies similar to portion 1. but changing temperatures at which the reaction takes topographic point. For each tally. solution A and B were prepared utilizing the recommended values from the lab manual.

We so place both solutions in an ice bath ( for the first 2 tallies ) and in a H2O bath ( for the staying tallies ) to acquire their temperatures to the same values as that of the water/ice in the bath. We besides used the temperature values suggested in the lab manual. When needed. we increased the temperature by heating the hot home base on which we placed our bath of adding ice regular hexahedrons into the bath. Once the thermometers in each solution and that in the bath reached the coveted value. I at the same time noted the clip on the lab clock and poured solution B into the flask incorporating solution B.

I recorded the clip from when I poured solution A into B to when I noticed a colour alteration from colorless to purple. I so used the informations obtained to plot a graph of ln ( K ) against the reciprocal of the temperature for all the six tallies. plus the mean value of K and temperature calculated from the first portion of the lab. This graph was so used to find the activation energy. Ea and the Arrhenius pre-exponential factor. A. We report an A value of and an activation energy value of 56. 80kJ/mol. This compares to theoretical value of 56. 5kJ/mol at 0. 53 % difference.


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