PDF Lesson

### Lessons 2: Fine-tuning Your Analysis of Solutions

In the previous lesson you estimated the unknown concentration of a solution by comparing values. In this lesson you’ll use some high-powered mathematics and graphical techniques to improve your ability to predict the unknown concentration of a solution.

### Doing the science

*You must have complete Lesson 1 and have your complete set of data to begin this lesson.*- Transfer your data from the table in Lesson 1 to Table 1 below. Please note that the order of the solutions’ concentrations in the data table has been reversed; so make sure that you record the correct voltage with the correct concentration.
- In Lesson 1, the laser shot light through the solutions. Some light passed through and some was absorbed by the solution. The % Transmission is a measure of how much light passed through the sample. Calculate the % Transmission of each solution using the following equation and record your results in Table 1.

% Transmission for a specific solution =voltage of a specific solutionvoltage of the 0% solutionx 100% - Absorbance is a measure of how much light is absorbed by a solution. Use the following equation to calculate the absorbance of each solution and record these values in Table 1. You’ll need a scientific calculator to complete this calculation.

Absorbance = log (voltage of the 0% solution/voltage of a specific solution) **Create a graph plotting the concentrations of the solutions on the***"x"*axis and absorbance on the*"y"*axis.**Use your graph to determine the concentration of***Unknown A or B*and record your results at the bottom of Table 1.