electromagnetic radiation of wavelenth 242nm is just sufficient to ionise the sodium atom
calculate the ionisation energy of sodium in KJ/mol .

Asked by patidarshm | 11th Dec, 2015, 11:51: AM

Expert Answer:

begin mathsize 11px style Energy space of space one space photon space of space the space radiation space having space wave space length space 242 space nm space is space just space sufficient space to space ionise space the space sodium space atom. Therefore comma space ionisation space energy space of space sodium space equals space Energy space of space one space photon space of space radiation space of space wavelength Energy space of space photon space equals space straight E space equals space straight h space straight c over straight lambda Where comma straight h space equals space 6.626 space cross times space 10 to the power of negative 34 end exponent space Js straight c space equals space 3 space cross times space 10 to the power of 8 space straight m divided by straight s straight lambda space equals space 242 space cross times space 10 to the power of negative 9 end exponent space straight m space Therefore comma space substituting space the space values space in space the space above space formula space we space get comma straight E space equals space fraction numerator 6.626 space cross times space 10 to the power of negative 34 end exponent space Js space cross times space 3.0 space cross times space 10 to the power of 8 space end exponent ms to the power of negative 1 space end exponent over denominator 242 space cross times space 10 to the power of negative 9 end exponent space straight m end fraction space space space equals 8.22 space cross times space 10 to the power of negative space space 19 end exponent space straight J divided by photon space space space equals space 8.22 space cross times space 10 to the power of negative 22 end exponent space kJ divided by photon Therefore comma space ionisation space energy space per space mole space equals space 8.22 space cross times space 10 minus 22 space cross times space 6.022 space cross times space 10 to the power of 23 space kJ divided by mol space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals space 495 space kJ divided by mol end style

Answered by Hanisha Vyas | 11th Dec, 2015, 06:24: PM