Determination of Rate Law
Abstract: The reaction used to determine the experimental rate law of is 2I-(aq) + H2O2(aq) I2(aq) + 2H2O2(l). The rate law determined experimentally is rate= k[I-]1.017[H2O2]0.927. Additionally by performing essentially the same experiments but with temperature changes one can determine how k is affected by temperature changes and the new activation energy. Also, from graphs the activation energy was determined to be 33.3 kJ/mol.
INTRODUCTION:
The rate of a chemical reaction often depends on reactant concentrations, temperature, and the presence of a catalyst. Additionally, the rate law is determined mathematically only from experimental data. The reaction investigated in this experiment is:
2I-(aq) + H2O2(aq) I2(aq) + 2H2O2(l) (1)
In order to determine the details of the rate law for the reaction above, the rate must be measured through experiment. The orders are in the form of variables because these must be determined through calculations from the data collected at the end of the experiment trials and then graphed. For this experiment the rate law is: rate= k[I-]x[H2O2]y (2)
The rate of reaction (1) can be determined by analyzing the amount of iodine (I2) formed. Two chemical reactions are useful to determining the amount of iodine is produced.
I2(aq) + 2S2O32-(aq) 2I-(aq)+S4O62-(aq) (3)
I2(aq) + starch I2 *starch(blue complex) (4)
Reaction (4) is an iodine-starch reaction, used solely to determine when the production of iodine is occurring by turning a clear colorless solution to a blue color. Without reaction (4) it would be very difficult to determine how much iodine is being produced, due to how rapidly thiosulfate and iodine react. However reaction (4) does not determine the amount of iodine produced, it only determines when iodine is present in solution. Essentially reaction (3) is used to determine how much iodine is produced.
To understand how the rate constant (k) is temperature dependent, another set of data can be recorded
INTRODUCTION:
The rate of a chemical reaction often depends on reactant concentrations, temperature, and the presence of a catalyst. Additionally, the rate law is determined mathematically only from experimental data. The reaction investigated in this experiment is:
2I-(aq) + H2O2(aq) I2(aq) + 2H2O2(l) (1)
In order to determine the details of the rate law for the reaction above, the rate must be measured through experiment. The orders are in the form of variables because these must be determined through calculations from the data collected at the end of the experiment trials and then graphed. For this experiment the rate law is: rate= k[I-]x[H2O2]y (2)
The rate of reaction (1) can be determined by analyzing the amount of iodine (I2) formed. Two chemical reactions are useful to determining the amount of iodine is produced.
I2(aq) + 2S2O32-(aq) 2I-(aq)+S4O62-(aq) (3)
I2(aq) + starch I2 *starch(blue complex) (4)
Reaction (4) is an iodine-starch reaction, used solely to determine when the production of iodine is occurring by turning a clear colorless solution to a blue color. Without reaction (4) it would be very difficult to determine how much iodine is being produced, due to how rapidly thiosulfate and iodine react. However reaction (4) does not determine the amount of iodine produced, it only determines when iodine is present in solution. Essentially reaction (3) is used to determine how much iodine is produced.
To understand how the rate constant (k) is temperature dependent, another set of data can be recorded