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# Emission Line Energy

The Rydberg equation expresses the wavelength, λ, of emitted light based on the initial and final energy states (ni and nf) of an electron in a hydrogen atom:

1λ=RH×(1nf2−1ni2)

where RH=1.097×107 m−1=1.097×10−2 nm−1.

You may also see this equation written as

1λ=−RH×(1ni2−1nf2)

Since

(1nf2−1ni2)=−(1ni2−1nf2)

the two formulas are equivalent and sometimes used interchangeably. It can help to remember that when light is emitted, E is negative. When light is absorbed, E is positive.

With some manipulation, the Rydberg equation can be rewritten in the form

E=constant×(1nf2−1ni2)

which allows you to calculate the energy of the emitted light. What is the value of the constant needed to complete this equation?

What is the change in energy, ΔE, in kilojoules per mole of hydrogen atoms for an electron transition from n=8 to n=2?

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Posted on October 3, 2013, in Question and tagged , , , , , , , , . Bookmark the permalink. 2 Comments.

• ### Comments 2

1. Rant4u

2.18×10^−18J

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2. Rant4u

-308 kJ/mol

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