# Determination of a Rate Law

Pages: 3 (838 words) Published: May 1, 2008
Abstract
The rate of a chemical reaction may depend upon reactant concentrations, temperature, and the presence of catalysts. The results from the experiment show the orders are k [I]0[H2O2] and overall order is 1 and the reaction rate is 0.0500/Δt. The rate constant is 1.04 x 10-2 s-1. Introduction

The rate of a chemical reaction may depend upon reactant concentrations, temperature, and the presence of catalysts. At a fixed temperature, the rate of a reaction may be mathematically described by a rate law. In this experiment the rate law for the chemical reaction, 2I + H2O2  I2 + 2H2O. The reaction rate must be measured and the values of the constant (k) and order (p and q) for the rate law k [I]p [H2O2] q can be calculated. Experimental

Table 1: Composition of experiment 1 solutions
Trial #Solution ASolution B
Buffer0.3 M KIStarch0.02 M Na2S2O3DI Water0.1 M H2O2TempTime 15.00mL2.00mL0.40mL5.00mL21.6mL6.00mL22°C320s
25.00mL4.00mL0.40mL5.00mL19.6mL6.00mL21°C255s
35.00mL6.00mL0.40mL5.00mL17.6mL6.00mL20.5°C199s
45.00mL6.00mL0.40mL5.00mL13.6mL10.00mL20.5°C120s
55.00mL6.00mL0.40mL5.00mL9.6mL14.00ml21°C92s
Prepare each solution as indicated in Table 1. For solution A prepare in a clean beaker and swirl to mix thoroughly. Then add Solution B and begin timing the reaction. At the first sign of the blue color stop the clock. Record the time elapsed in seconds and the temp as done in Table 1. Table 2: Composition of experiment 2 solutions

Trial #Solution ASolution B
Buffer0.3 M KIStarch0.02 M Na2S2O3DI Water0.1 M H2O2TempTime 15.00mL6.00mL0.40mL5.00mL13.6mL10.00mL1.5°C568s
25.00mL6.00mL0.40mL5.00mL9.6mL14.00mL1.5°C455s
35.00mL2.00mL0.40mL5.00mL21.6mL6.00mL42.0°C127s
45.00mL4.00mL0.40mL5.00mL19.6mL6.00mL40.0°C70s
55.00mL6.00mL0.40mL5.00mL17.6mL6.00mL31.0°C90s
65.00mL4.00mL0.40mL5.00mL19.6mL6.00mL31.0°C148s
Prepare two water baths...