A ground-state H atom absorbs a photon of wavelength 94.91 nm, and its electron attains a higher energy level. The atom then emits two photons: one of wavelength 1281 nm to reach an intermediate level, and a second to reach the ground state.
(a) What higher level did the electron reach?
(b) What intermediate level did the electron reach?
(c) What was the wavelength of the second photon emitted?

Respuesta :

Answer:

Explanation:

94.91 nm = 1237.5 / 94.91 eV

= 13.038 eV

Energy of ground state = - 13.6 eV

Energy of higher state to which it jumped

= - 13.6 + 13.038

= -  .562 eV

If n be the orbit to which it jumped

13.6 / n² = .562

n = 5 ( approx )

b )

1281 nm = 1237.5 / 1281

= .966 eV

Energy of second photon = 13.038 - .966

= 12.072 eV

Wavelength of second photon

= 1237.5 / 12.072

= 12.51 nm

b ) Energy of intermediate level

= - 0.562 - .966 eV

= - 1.528 eV

If it be n th level

13.6 / n² = 1.528

n = 3

A) The higher level that the electron reached from ground state is; n = 5

B) The intermediate level that the electron reached from ground state is; n = 3

C) The wavelength of the second photon emitted is; λ = 103 nm

A) We are given;

Wavelength of photon absorbed by ground state H atoms; λ_g = 94.91 nm = 94.91 × 10⁻⁹ m

Formula to get the higher level is Rydberg's formula;

1/λ = R(1/n₁² - 1/n₂²)

where;

R is rydberg constant = 1.097 × 10⁷ m⁻¹

Thus;

1/(94.91 × 10⁻⁹) = 1.097 × 10⁷(1/1² - 1/n₂²)

0.9605 = 1 - 1/n₂²

1/n₂² = 1 - 0.9605

1/n₂² = 0.0395

n₂ = √(1/0.0395)

n₂ ≈ 5

B) We want to find the intermediate level where wavelength = 1281 nm = 1281 × 10⁻⁹ m

Thus;

1/(1281 × 10⁻⁹) = 1.097 × 10⁷(1/n₂² - 1/5²)

0.0712 = 1/n₂² - ¹/₂₅

1/n₂² = 0.0712 + ¹/₂₅

1/n₂² = 0.1112

n₂ = √(1/0.1112)

n₂ ≈ 3

C) Formula for energy of photon is;

E = hc/λ

where;

h is Planck's constant = 6.626 × 10⁻³⁴ m².kg/s

c is speed of light = 3 × 10⁸ m/s

Thus;

E = (6.626 × 10⁻³⁴ × 3 × 10⁸)/(1281 × 10⁻⁹)

E = 1.552 × 10⁻¹⁹ J

The energy at ground state is;

E = (6.626 × 10⁻³⁴ × 3 × 10⁸)/(94.91 × 10⁻⁹)

E = 20.944 × 10⁻¹⁹ J

Thus;

Energy of second photon = (20.944 × 10⁻¹⁹) - (1.552 × 10⁻¹⁹)

Energy of second photon = 19.352 × 10⁻¹⁹ J

Wavelength of second photon emitted is;

λ = hc/E

λ = (6.626 × 10⁻³⁴ × 3 × 10⁸)/19.352 × 10⁻¹⁹

λ = 103 nm

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