Question

A 9.00 mL ampule of a 0.140 M solution of naphthalene in hexane is excited with a flash of light. The naphthalene emits 11.3 J of energy at an average wavelength of 349 nm. What percentage of the naphthalene molecules emitted a photon?

Answer #1

Given:

lambda = 3.49*10^-7 m

1st calculate energy of 1 photon

Given:

lambda = 3.49*10^-7 m

use:

E = h*c/lambda

=(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 = 11.3/5.696*10^-19

= 1.984*10^19

So, 1.984*10^19 molecules have emitted photon

Lets now calculate the total number of molecules available.

Use:

number of mol = Molarity * volume in L

= 0.140 M * 0.009 L

= 1.26*10^-3 mol

number of molecule present = number of mol * Avogadro’s number

= 1.26*10^-3 * 6.022*10^23

= 7.59*10^20

% of molecules emitting photons = number of molecules emitting photon * 100 / total number of molecule present

= (1.984*10^19)*100 / (7.59*10^20)

= 2.61 %

Answer: 2.61 %

A 9.00 mL ampule of a 0.150 M solution of naphthalene in hexane
is excited with a flash of light. The naphthalene emits 18.4 J of
energy at an average wavelength of 349 nm.
What percentage of the naphthalene molecules emitted a
photon?

A 6.00 mL ampule of a 0.120 M solution of naphthalene in hexane
is excited with a flash of light. The naphthalene emits 18.3 J of
energy at an average wavelength of 349 nm. What percentage of the
naphthalene molecules emitted a photon?

A 4.00 mL ampule of a 0.130 M solution of naphthalene in hexane
is excited with a flash of light. The naphthalene emits 12.8 J of
energy at an average wavelength of 349 nm. What percentage of the
naphthalene molecules emitted a photon?

A 5.00 ml ampule of a 0.100 M solution of naphthalene in hexane
is excited with a flash of light. The naphthalene emits 15.5 J of
energy at an average wavelength of 349 nm. What percentage of
naphthalene molecules emitted a photon?

A 3.00 mL ampule of a 0.120 M solution of naphthalene in hexane
is excited with a flash of light. The naphthalene emits 10.8 J of
energy at an average wavelength of 349 nm.
What percentage of the naphthalene molecules emitted a
photon?

A 8.00 mL ampule of a 0.100 M solution of naphthalene in hexane
is excited with a flash of light. The naphthalene emits 18.5 J of
energy at an average wavelength of 349 nm. What percentage of the
naphthalene molecules emitted a photon?

A
3.00 mL ampule of 0.120 M solution of naphthalene in hexane is
excited with a flash of light. The naphthalene emits 14.2 J of
energy at an average wavelength of 349 nm. What percentage of the
naphthalene molecules emitted a photon?

A 7.00 mL ampule of a 0.130 M solution of naphthalene in hexane
is excited with a flash of light. The naphthalene emits 13.0 J of
energy at an average wavelength of 349 nm. What percentage of the
naphthalene moleules emitted a photon?

A 5.25mL sample of a 0.100M solution of an aromatic hydrocarbon
dissolved in hexane is excited with a flash of light. The aromatic
compound emits 16.2J of energy at an average wavelength of 379
nm.
-What percentage of the aromatic compound molecules emitted a
photon?

An electron in an excited state
of a hydrogen atom emits two photons in succession, the first at
3037 nm and the second at 94.92 nm, to return to the ground state
(n=1). For a given transition, the wavelength of the emitted photon
corresponds to the difference in energy between the two energy
levels.
What were the principal quantum numbers of the initial and
intermediate excited states involved?

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