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I https:/Isession masteringchemistry.commyct/temview7assignmentProblemlb-867311268offset-next Exercise 7.90-Enhanced-with Feedback re CH 07 HW Exercise 7.90- Enhanced- with Feedback Part A A 7.00 mL ampule of a 0.120 M solution of naphthalene in hexane is excited with a flash of light. The naphthalene emits 14.8 J of energy at an average wavelength of 349 nm. What percentage of the naphthalene molecules emitted a photon? Express your answer using three significant figures You may want to reference ( pages 296-324) Chapter 7 while completing this problem. Submit My Answers Give Up Incorrect: Try Again: 4 attempts remainingExplanation / Answer
A)
we have:
wavelength = 3.49*10^-7 m
1st calculate energy of 1 photon
we have:
wavelength = 3.49*10^-7 m
we have below equation to be used:
Energy = Planck constant*speed of light/wavelength
=(6.626*10^-34 J.s)*(3.0*10^8 m/s)/(3.49*10^-7 m)
= 5.696*10^-19 J
number of photon = total energy/energy of 1 photon
n = 14.8/5.696*10^-19
= 2.598*10^19
number of mol of Napthalene = M*V
= 0.120 M * 7.00 mL
= 0.84 mmol
= 8.4*10^-4 mol
we have below equation to be used:
number of molecules = number of mol * Avogadro’s number
number of molecules = 8.4*10^-4 * 6.022*10^23 molecules
number of molecules = 5.058*10^20 molecules
% of molecules emitted = number of photons * 100 / number of molecules
= (2.598*10^19)*100/(5.058*10^20)
= 5.14 %
Answer: 5.14 %