Map Sapling Learning macmillan learning this question has been customized by Ele

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Map Sapling Learning macmillan learning this question has been customized by Elena Smirnova at University of Manitoba excited hydrogen atom in the n- 2 state relaxes back down to its ground state, emitting a photon. This photon is absorbed by a nearby H2 molecule, causing it to dissociate into two hydrogen atoms Determine the energy and wavelength of the emitted photon, in units of joules and nanometers, respectively. Energy of the photon Number 5.45 x 1019 J Wavelength of the photon: Number 364 nm The bond energy for an H2 molecule is 432 kJ/mol. Upon dissociation of one of the H2 molecules (from above) into two hydrogen atoms, all excess energy is converted into the kinetic energy of the two hydrogen atoms. Determine the total kinetic energy, in units of joules, of the two hydrogen atom:s Number View Previous View Solution View Next Fxit

Explanation / Answer

a) Rydberg equation for Energy of photon emited from hydrogen atom

E = R ( 1/nf2 - 1/ni2)

R = Rydberg constant for energy,2.178×10^-18J

E = 2.178×10^-18J(1/1^2 - 1/2^2)

= 1.63 × 10^-18J

b) Rydberg equation for wavelength of emission of Hydrogen atom is

1/wavelength = R(1/nf2 - 1/ni2)

Where , R= Rydberg constant = 1.097×10^7m^-1

1/wavelength = 1.097×10^7 m^-1(1/1^2 - 1/2^2)

= 0.82275×10^-7m^-1

Wavelength = 1/(0.82275×10^7m^-1)

= 1.2154×10^-7m

= 121.5×10^-9m

= 121.5nm

c) 1mole = 6.022×10^23molecule

Therefore,

Dissociation energy of one molecule of H2= 432kJ/6.022×10^23=7.17×10^-22kJ =7.17×10^-19J

Energy of Photon = 1.63×10^-18J

Kinetic energy = Energy of photon - Dissociation energy

= 1.63×10^-18J - 7.17×10^-19J

= 9.13 ×10^-19J

  

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