Question

Determine the effect of the following errors on the measured absorbance for a pink colored 0.50 m solution of cobalt (ii) chloride, cocl2 (aq). a) you rinsed the cuvette with water before adding the sample of cocl2 (aq). b) you used a cuvette that had previously contained 0.80 m cocl2 (aq). c) the solution was incorrectly made and the concentration was 0.05 m. d) the spectrophotometer was calibrated with 0.05 m cocl2 (aq) solution instead of water. e) you used a cuvette that was scratched on the sides.

Answer 1

The effect of errors such as improper rinsing, use of a contaminated cuvette, incorrect solution concentration, improper spectrophotometer calibration, and using a scratched cuvette could lead to falsely low or high absorbance measurements, ultimately affecting the accuracy of determining the concentration of the cobalt (II) chloride solution.

Step-by-step explanation:

To determine the effect of errors on the measured absorbance for a pink colored 0.50 M solution of cobalt (II) chloride, CoCl2 (aq), various scenarios can be analyzed:

• Rinsing the cuvette with water before adding the sample could result in dilution of the sample, potentially causing a lower measured absorbance than the actual value.
• Using a cuvette that had previously contained a higher concentration of CoCl2 could contaminate the lower concentration solution, resulting in higher measured absorbance.
• If the solution was incorrectly made at a lower concentration (0.05 M), the measured absorbance would be significantly lower than expected for a 0.50 M solution due to the directly proportional relationship between concentration and absorbance.
• Calibrating the spectrophotometer with a 0.05 M CoCl2 solution instead of water will affect the baseline absorbance readings, causing incorrect absorbance values for all samples measured thereafter.
• Using a scratched cuvette could scatter light and distort the measurement, leading to erroneous absorbance readings.