Question

Suppose you plan to use colorimetry to measure the concentration of cobalt (II) chloride, which forms a red solution. What part of procedure you would change? (Hint: you may use pre-lab computer simulation to answer this question). Justify your answer.

Answer 1

OBJECTIVE- to test absorbance of cobalt(II) chloride solution, and determine its concentration.

The intensity of color absorbed it directly related to the concentration of test factor producing the color. Since our sample produces red solution turns pink upon exposure to moist air but turns blue at high temperatures, cobalt chloride complex is in equilibrium with water so if more dilute solution turns more pink, a wavelength in green region is selected to analyze as red color solution absorbs green color.

proposed change-

is excess ammonia is added in which ammonia reacts with cobalt and forms ammonia cobalt complex and gives brown color change.More reliable