Question

In: Chemistry

1, Which carries more energy, yellow light with a wavelength of 580 nm or green light...

1, Which carries more energy, yellow light with a wavelength of 580 nm or green light with a wavelength of 560 nm? (Explain or show a calculation).

2,Why do we see a characteristic color (in the flame) for each cation?

4,The energy of an electron in n = 1 for a hydrogen atoms was found to be -2.179 x10-18 J/atom. Convert this value to kJ/mole.

5,Calculate the energy of light emitted when an electron changes from n = 3 to n = 1 in the hydrogen atom. In what region of the spectrum is this radiation found?

Expert Solution

1) Which carries more energy, yellow light with a wavelength of 580 nm or green light with a wavelength of 560 nm? (Explain or show a calculation).

Answer: The energy, wavelength relationship can be shown as,

E = hc/

Thus, energy is inversely proportional to the wavelength or as the wavelength increases, energy decreases. Therefore, here, the green light has a higher energy

2) Why do we see a characteristic colour (in the flame) for each cation?

When elements are heated, some of the electrons in the atoms are excited to the higher energy levels. When this electron return to the ground state or a lower energy level, it emits a quantum of energy. The wavelength and thereby colour of the emitted light depend on the difference in energy levels. Since each element has its own characteristic energy levels, each cation has a characteristic colour

4) The energy of an electron in n = 1 for hydrogen atoms was found to be -2.179 x10^-18 J/atom. Convert this value to kJ/mole.

E = (-2.179 x 10^-18 J/atom)[(1 kJ)/(1000 J)][(6.022 x 10²³ atoms)/(1 mol)] = -1,312 kJ/mole

5) Calculate the energy of light emitted when an electron changes from n = 3 to n = 1 in the hydrogen atom. In what region of the spectrum is this radiation found?

We have,

E = hv = -13.6 eV x [(1/n₁²) - (1/n₂²)] [Note: -13.6 eV = - 2.179 x 10^-19 J]

E = -2.179 x 10^-19 J[(1/1) - (1/9)] = -2.179 x 10^-19 J(8/9) = 1.937 x 10^-18 J

This radiation found in the UV region (Lyman series)

queen_honey_blossom answered 2 years ago

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