chemistry 2
Reaction Order and Rate Laws
Hands-On Labs, Inc.
Version 42-0195-00-02
Lab Report Assistant
This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.
Exercise 1: Determining the Rate Laws of the Reaction between HCl and Na2S2O3
Data Table 1. Varying Concentrations of 1.0 M HCl.
Concentrations | ||||||||||||||
# of drops | # of drops | # of drops | Stock Solution | Stock Solution | Reaction (after mixing in well) | Reaction (after mixing in well) | Reaction Time (seconds) | Reaction Rate (sec-1) | ||||||
Well # | HCl | H2O | Na2S2O3 | HCl | Na2S2O3 | HCl | Na2S2O3 | Trial 1 | Trial 2 | Average | ||||
C1, D1 | 12 | 8 | 1M | 0.3M | ||||||||||
C2, D2 | 6 | 8 | 1M | 0.3M | ||||||||||
C3, D3 | 8 | 1M | 0.3M |
Data Table 2. Varying Concentrations of 0.3 M Na2S2O3.
Concentrations | ||||||||||||||
# of drops | # of drops | # of drops | Stock Solution | Stock Solution | Reaction (after mixing in well) | Reaction (after mixing in well) | Reaction Time (seconds) | Reaction Rate (sec-1) | ||||||
Well # | HCl | H2O | Na2S2O3 | HCl | Na2S2O3 | HCl | Na2S2O3 | Trial 1 | Trial 2 | Average | ||||
C4, D4 | 12 | 1M | 0.3M | |||||||||||
C5, D5 | 8 | 6 | 1M | 0.3M | ||||||||||
C6, D6 | 4 | 1M | 0.3M |
Questions
Determine the Reaction Order for HCl using calculations described in the Background section. Show your work. Note that your answer will probably not be an even whole number as it is in the examples, so round to the nearest whole number.
Determine the Reaction Order for Na2S2O3 using calculations described in the Background section. Show your work. Note that your answer will probably not be an even whole number as it is in the examples.
Write the rate law for the reaction between HCl and Na2S2O3.
Using the following rate law, and the experimental values given, calculate k:
Experiment | [F2] (M) | [ClO2] (M) | Initial rate (M/s) |
0.5 | 0.5 | 0.300 M/s | |
0.8 | 0.8 | 0.768 M/s | |
0.5 | 0.8 | 0.480 M/s |
Describe sources of error in this experiment?