11.Now collect absorbance-concentration data for the three beakers of equilibrium mixtures.a. Using the solution in Beaker A, rinse the cuvette twice with ~1 mL amounts and then fill it 3/4 full. Wipe the outside with a tissue and place the cuvette in the device.b. Write down, in your data table, the absorbance of the sample in Beaker A.c. Use your best-fit line equation to find the FeSCN2+concentration for the sample in Beaker A. Record the concentration in your data tabled. Discard the cuvette contents down the sink. Rinse and fill the cuvette with the solution in Beaker B and place it in the device. After the reading stabilizes, write down the absorbance in your data table and determine the concentration of the sample.e. Repeat Step d for the mixtures in Beaker C.The Determination of an Equilibrium ConstantAdvanced Chemistry with Vernier 10 - 7 DATA TABLE Part I Temperature: °C Beaker [FeSCN 2+ ] Absorbance 1 2 3 4 Linear Regression Equation Part II Beaker Absorbance [FeSCN 2+ ] at equilibrium A B C Computer 10 10 - 8 Advanced Chemistry with Vernier Calculating Equilibrium Concentrations A common method that is used to organize and calculate the concentrations of the species in an equilibrium system is colloquially known as an I.C.E. chart. “I.C.E” stands for Initial concentration, Change in concentration, and the Equilibrium concentration. The initial concentrations of the Fe 3+ and the SCN – ions can be calculated from the mixing chart in Part II, Step 10. You have already determined the equilibrium concentration of the FeSCN 2+ ions by completing the analysis in Part II. The rest is a little bit of math.
BEAKER A Fe 3+ SCN – FeSCN 2+ Initial 0.00 Change Equilibrium BEAKER B Fe 3+ SCN – FeSCN 2+ Initial 0.00 Change Equilibrium BEAKER C Fe 3+ SCN – FeSCN 2+ Initial 0.00 Change Equilibrium The Determination of an Equilibrium Constant Advanced Chemistry with Vernier 10 - 9 DATA ANALYSIS 1. (Part II) Use your data to determine the [Fe3+], [SCN–], and [FeSCN2+] at equilibrium for each ofthe mixtures that you prepared in Part II. Complete the table below and give an example of yourcalculations. 2. Calculate the value of Keq for the reaction. Explain how you used the data to calculate Keq .
You've reached the end of your free preview.
Want to read all 4 pages?
- Spring '20
- Chemistry, Test Equilibrium Systems