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Find the minimum photon frequency for a reaction

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Chemical and Physical Foundations

A photochemical reaction requires a minimum energy of 3.3×10−19 J3.3 \times 10^{-19}\ \text{J} from a single photon. Given that Planck's constant is 6.6×10−34 J⋅s6.6 \times 10^{-34}\ \text{J}\cdot\text{s}, what is the minimum frequency of electromagnetic radiation that can initiate the reaction?

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Answer: B (5.0×1014 Hz5.0 \times 10^{14}\ \text{Hz})

The energy of a photon is given by E=hfE=hf. Therefore, the minimum frequency is ff=Eh{}=\frac{E}{h}=3.3×10−19 J6.6×10−34 J⋅s{}=\frac{3.3 \times 10^{-19}\ \text{J}}{6.6 \times 10^{-34}\ \text{J}\cdot\text{s}}=5.0×1014 Hz{}=5.0 \times 10^{14}\ \text{Hz}. Radiation below this frequency does not provide the required energy in a single photon.

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