Beer's Law Investigations
Recommended for grades 9–16.
Introduction
The primary objective of this Preliminary Activity is to determine the concentration of an unknown copper (II) sulfate solution. You will use a Colorimeter (a side view is shown above). In this device, red light from the LED light source will pass through the solution and strike a photocell. The CuSO4 solution used in this experiment is blue. A higher concentration of the colored solution absorbs more light (and transmits less) than a solution of lower concentration. The Colorimeter monitors the light received by the photocell as percent transmittance.
You will prepare five copper (II) sulfate solutions of known concentration (standard solutions). Each solution is transferred to a small, rectangular cuvette that is placed into the Colorimeter. The amount of light that penetrates the solution and strikes the photocell is used to compute the absorbance of each solution. When you graph absorbance vs. concentration for the standard solutions, a direct relationship should result. The direct relationship between absorbance and concentration for a solution is known as Beer’s law.
Objectives
The primary objective of this Preliminary Activity is to determine the concentration of an unknown copper (II) sulfate solution.
After completing the Preliminary Activity, you will first use reference sources to find out more about solutions, solution concentration, and Beer’s law investigations before you choose and investigate a researchable question utilizing Beer’s law technique.
Sensors and Equipment
This investigation requires each of the following Vernier sensors and equipment (unless otherwise noted):
Additional Requirements
You may also need an interface and software for data collection. What do I need for data collection?
Download Experiment Preview
The student-version preview includes:
- Step-by-step instructions for the Preliminary Activity
- List of materials and equipment
Note: The experiment preview of the Preliminary Activity does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.
Standards Correlations
See all standards correlations for Investigating Chemistry through Inquiry »
Included in the Lab Book
Vernier lab books include a CD with word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.