Question

Questions:

1. Explain two things in the procedure that may reduce the final percent yield.
2. The K₃[Fe(C₂O₄)₃]·3H₂O crystals are green. The compound absorbs light at 675 nm.
   1. What color of light does this correspond to in the visual light section of the electromagnetic spectrum?

2. Compare your answer in part a to the observation of green crystals. Is the color you see the absorbed color or transmitted color?

Answer 1

Visual light spectrum is the observable region of the human eye in the electromagnetic spectrum.

The wavelength range of visual light spectrum is 380-720 nm.

Between this range of wavelengths we can observe many colors.

Violet color has the shortest wavelength and red has the longest wavelength in visible light.

When visible light of many frequencies or wavelengths fall on an object, the light may be absorbed or reflected or transmitted depending upon the nature of the atoms of the object and the frequency of light ray.

When visible light strikes an object, certain frequency of light (which matches with the natural frequency of atoms/molecules of the object)is absorbed.This absorbed light is not visible to our eyes.

The color of the object is reflected or transmitted light to our eyes by the object.

For example if an object appears red, that means it absorbs all the other frequencies of visible light except for red.Hence, it appears red.

a. It is given that the compound absorbs light ray at 675 nm which corresponds to red light in the visual light section.

So, the given compound absorbs red color light.

b.

It is given that the crystals of K₃[Fe(C₂O₄)₃]·3H₂O appear green.

That means K₃[Fe(C₂O₄)₃]·3H₂O absorb red color but does not absorb green color.

This green color is the transmitted light by the crystals to our eye.

Hence, green color is the transmitted light by K₃[Fe(C₂O₄)₃]·3H₂O crystals.

Preparation of K₃[Fe(C₂O₄)₃]·3H₂O crystals :