Table of contents

1. Chemical Measurements1h 50m
2. Tools of the Trade1h 17m
3. Experimental Error1h 52m
4 & 5. Statistics, Quality Assurance and Calibration Methods1h 57m
6. Chemical Equilibrium3h 41m
7. Activity and the Systematic Treatment of Equilibrium1h 0m
8. Monoprotic Acid-Base Equilibria1h 53m
9. Polyprotic Acid-Base Equilibria2h 17m
10. Acid-Base Titrations2h 37m
11. EDTA Titrations1h 34m
12. Advanced Topics in Equilibrium1h 16m
13. Fundamentals of Electrochemistry2h 19m
14. Electrodes and Potentiometry41m
15. Redox Titrations1h 14m
16. Electroanalytical Techniques57m
17. Fundamentals of Spectrophotometry50m

1. Chemical Measurements

Volumetric Analysis

Analytical Chemistry

1. Chemical Measurements

Volumetric Analysis

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Multiple Choice

When creating a calibration plot in volumetric analysis, how can you determine the concentration of Fe(SCN)2+(aq) in an unknown sample?

Estimate the concentration based on the color intensity by eye.

Calculate the concentration using the initial volumes of Fe3+ and SCN- added.

Directly weigh the Fe(SCN)2+(aq) in the solution.

Measure the absorbance of the unknown and use the calibration plot to find its concentration.

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Verified step by step guidance

Step 1: Understand the concept of a calibration plot. A calibration plot is a graph that relates the absorbance of a solution (measured using a spectrophotometer) to the concentration of the analyte. This is based on Beer-Lambert's law, which states that absorbance is directly proportional to concentration.

Step 2: Prepare a series of standard solutions with known concentrations of Fe(SCN)2+(aq). Measure the absorbance of each standard solution using a spectrophotometer at the wavelength where Fe(SCN)2+(aq) absorbs light most strongly.

Step 3: Plot the absorbance values of the standard solutions against their respective concentrations to create the calibration plot. Ensure the plot is linear, as Beer-Lambert's law applies within a linear range.

Step 4: Measure the absorbance of the unknown sample using the same spectrophotometer and wavelength used for the standard solutions.

Step 5: Use the calibration plot to determine the concentration of Fe(SCN)2+(aq) in the unknown sample. Locate the absorbance value of the unknown sample on the y-axis of the plot, then trace horizontally to the calibration line and vertically down to the x-axis to find the corresponding concentration.