Question

Given the stretching frequencies for the C–H bonds shown in green, arrange the corresponding bonds in order of increasing strength.

Answer 1

If you are based on this graph: http://d2vlcm61l7u1fs.cloudfront.net/media/b24/b24a685f-fc36-4bbd-baaf-3c20e31c2c73/phpU1UjW1.png we can say that bond B goes first as it corresponds to 2850 cm -1 which is the lowest rate, the next bond will be A as it corresponds to 3080 cm -1 and finally it will be C bond that corresponds to the highest number that is 3300 cm -1

Answer 2

The right answer is B (2850cm-1) > A (3080cm-1) > C (3300cm-1)

It is possible to reason in terms of wavelength λ rather than frequency η (which is the inverse of the wavelength  (1 / λ)).

In the case of an electromagnetic wave propagating in a vacuum, the two quantities are linked by the relation: η = c / λ.

Planck-Einstein's relation is then written:

E = h * c /  λ

where "C" is the celerity of light in the void.

In this form, the relationship indicates that the energy of a photon is inversely proportional to its wavelength. So frequency is directly proportional to energy.

Thus, radiation with a shorter wavelength than the visible (gamma rays, X-rays, ultraviolet rays) is much more energetic than long-wave radiation (infrared rays, microwaves, radio waves). where an interaction with the material radically different.