Question

A student uses visible spectrophotometry to determine the concentration of CoCl2(aq) in a sample solution. First the student prepares a set of CoCl2(aq) solutions of known concentration. Then the student uses a spectrophotometer to determine the absorbance of each of the standard solutions at a wavelength of 510nm and constructs a standard curve. Finally, the student determines the absorbance of the sample of unknown concentration.

A wavelength of 510nm corresponds to an approximate frequency of 6×1014s−1. What is the approximate energy of one photon of this light?

9×1047J
3×1017J
5×10−7J
4×10−19J

Answer 1

E = 4 × 10⁻¹⁹ J

Step-by-step explanation:

It is given that,

Wavelength = 510 nm

Frequency =
`6* 10^(14)\ Hz`

We need to find the approximate energy of one photon of this light. The formula for the energy of a photon is given by :

`E=hf\\\\=6.63* 10^(-34)* 6* 10^(14)\\\\=3.97* 10^(-19)\ J`

or

E = 4 × 10⁻¹⁹ J

Hence, the correct option is (d).