General Chemistry Tutorial Questions

a) Find the wavelength (in nanometers) of light having frequency of 8.6 x 10^13 Hz?

Answer explanation

λ = 3 x 10e8 ms-1 / 8.6 x 10e13 s-1

= 3.48 x 10e-6 m

= 3488.37 nm

b) Find the frequency (in Hz) of light having wavelength of 566 nm?

Answer explanation

f = 3 x 10e8 ms-1 / 566 x 10e-9 m

= 5.3 x 10e14 s-1

A photon has a wavelength of 624 nm. Calculate the energy of the photon in joules.

Answer explanation

E = 6.626 x 10e-34 Js x (3.00 x 10e8 ms-1/ 624 x 10e-9 m)

= 3.1856 x 10e-19 J

The blue color of sky results from the scattering of sunlight by air molecules. The blue light has a frequency of about 7.5 x 10^14 Hz. a) Calculate the wavelength, in nanometers. b) Calculate the energy, in joules of a single photon.

Answer explanation

λ = 3 x 10e8 ms-1 / 7.5 x 10e14 s-1

= 4 x 10e-7 m

= 400 nm

E = (6.626 x 10e-34 J.s) (3 x10e8 m s-1) /

4 x 10e-7 m

= 4.969 x 10e-19 J

Calculate the wavelength (in nanometer) of photon emitted by a hydrogen atom when its electron drops from n=5 state to n=3 state.

Answer explanation

1/ λ = (1.097 x 10e7 m-1) (1/3^2 - 1/5^2)

λ = 1.28 x 10e-6 m

λ = 1280 m

Calculate the frequency (in Hz) of emitted photon when an electron drops from n=4 state to n=2 state in a hydrogen atom.

Answer explanation

1 / λ = 1.097 x 10e-7 m-1 (1/2^2 - 1/4^2)

λ = 4.86 x 10e-7 m

λ = 486.17 nm