Lab Procedure: Absorbance and Serial Dilution

Introduction

• The experiment involves measuring the absorbance of solutions using a cuvette and spectrophotometer.
• Solutions tested include copper(II) nitrate, cobalt(II) nitrate, and nickel nitrate.

Procedure

Measuring Absorbance

1. Copper (II) Nitrate

   • Measure 3 ml of copper(II) nitrate.
   • Invert and revert the cuvette to ensure even distribution.
   • Place the cuvette in the spectrophotometer to record absorbance.

2. Cobalt (II) Nitrate

   • Follow the same procedure as above with 3 ml of cobalt(II) nitrate.

3. Nickel Nitrate

   • Repeat the procedure with the nickel nitrate solution.

Part B: Absorbance of 0.25 M Cobalt (II) Nitrate

• Measure absorbance using the absorbance-transmittance chart.
• Measure again using a concentration of 0.25 M.

Serial Dilution

1. Preparing Dilutions

   • First Dilution

     • Mix 4 ml of cobalt nitrate with 6 ml of water.
     • Mix using a pipette and measure absorbance (0.394).

   • Second Dilution

     • Take the one molar solution, reduce to 5 ml, add 5 ml of water.
     • Mix and measure absorbance (0.209).

   • Third Dilution

     • Use the 0.05 M solution, reduce to 2 ml, add 8 ml of water.
     • Measure absorbance (0.048).

Unknown Solution

• Measure the absorbance of the unknown solution.
• Record absorbance (0.47) and use this data to deduce concentration using a calibration line.

Conclusion

• The experiment concluded with measuring the absorbance of unknown concentrations and using calibration for determining concentration.