Question

When a compound containing cesium ions is heated in a Bunsen burner flame, photons with an energy of 4.30 x 10-19 J are emitted. What is the wavelength and color of the cesium flame?

Answer 1

Answer: The wavelength of the flame is 462 nm and color of cesium flame is blue.

Explanation:

To calculate the wavelength, we use Planck's equation, which is:

$E=\frac{hc}{\lambda}$

where,

E = Energy of 1 photon = $4.30\times 10^{-19}J$

h = Planck's constant = $6.625\times 10^{-34}J.s$

c = speed of light = $3\times 10^8m/s$

$\lambda$ = wavelength = ?

Putting values in above equation, we get:

$4.30\times 10^{-19}=\frac{6.625\times 10^{-34}J.s\times 3\times 10^8m/s}{\lambda }\\\\\lambda=\frac{6.625\times 10^{-34}J.s\times 3\times 10^8m/s}{4.30\times 10^{-19}}=4.62\times 10^{-7}m=462nm$

The range of wavelength of blue light lies in range of 500 nm - 435 nm

The calculated wavelength lies in the above range. So, the color of the cesium flame is 462 nm

Hence, the wavelength of the flame is 462 nm and color of cesium flame is blue.