Question

Unknown element A produced a second line spectra with an energy of 2.796*10-19 J. What is the wavelength of this line in nm?

What is the color of the line?

Unknown element A produced a line spectra with an energy of 4.075*10-19 J. What is the wavelength of this line in nm?

What is the color of the line?

Which element do these lines spectra correspond to in both?

Answer 1

1) Given , E = 2.796 x 10^-19 J

We have the relation as-- E = hc /

=> = hc / E

=> =( 6.626 x 10^-34 Js * 3 x 10⁸ m/s ) / 2.796 x 10^-19 J

=> = 19.878 x 10^-26 / 2.796 x 10^-19 m

=> = 7.11 x 10^-7 m

=> = 711 x 10^-9 m

=> = 711 nm ( 1 nm = 10^-9 m)

The wavelength at 711 nm corresponds to red line.

2) Given , E = 4.075 x 10^-19 J

We have the relation as-- E = hc /

=> = hc / E

=> =( 6.626 x 10^-34 Js * 3 x 10⁸ m/s ) / 4.075 x 10^-19 J

=> = 19.878 x 10^-26 / 4.075 x 10^-19 m

=> = 4.88 x 10^-7 m

=> = 488 x 10^-9 m

=> = 488 nm ( 1 m = 10^-9 nm)

The wavelength at 488 nm corresponds to blue line.

This element can be Mercury.