Questions (put on separate paper 1. If you had a sample which contained both cop

Question

Questions (put on separate paper 1. If you had a sample which contained both copper ion and cobalt ion, what wavelength ranges would you expect to show significant absorbance? 2. A particular substance absorbs very strongly at 620 nm. At a concentration of 0.100 M, this substance has an absorbance of0.835 at 620 nm. a. Assuming that the path length is 1.00 cm, calculate the value of the molar absorptivity coefficient, E. b. What would be the absorbance (at 620 nm) of a solution of the same substance with a concentration of 0.140 M using the same path length?

Explanation / Answer

1. If our sample has Copper and cobalt ions in solution, color of solution will be blue or pink.

We perceive, Copper ion solutions as blue, because they absorb orange color at 600 nm. Therefore, copper ion solutions will show significant absorption at 600 nm.

In case of Cobalt ions, solutions are pink/red, because solution absorbs blue-green color at 490 nm, which shows red color. Cobalt ions will show significant absorption around 490 nm.

2.

Molar absorptivity coefficient can be calculated by formula, e = A/cl

Where e is Molar absorptivity coefficient, A is absorbance, c is concentration and l is path length

e = 0.835 / 0.1 * 1 = 8.35 L /mol cm

Absorbance for same solution with 0.140 M

A = ecl = 8.35 * 0.140 * 1 = 1.169

Absorbance has no units.

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.