Question

Calculate the energy emitted when electrons of 1 g atom of hydrogen

Answer 1

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Calculate the energy emitted when electrons of 1.0g atom of hydrogen under go transition giving the spectral lines of lowest energy in the visible region of its atomic spectra.RH=1.1×107m−1,c=3×108msec−1RH=1.1×107m−1,c=3×108msec−1 and h=6.62×10−34Jsech=6.62×10−34Jsec

(a)182.5KJ(b)205KJ(c)150.89KJ(d)190.36KJ(a)182.5KJ(b)205KJ(c)150.89KJ(d)190.36KJ

jeemain chemistry physical-chemistry class11 unit2atomic-structure bhor's-model q92 difficult

  

 

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asked Jan 15, 2014 by sreemathi.v 
edited Jul 15, 2016 by sharmaaparna1



2 Answers

For visible line spectrum,(i.e) Balmer series n1=2n1=2.Also for minimum energy transition n2=3n2=3

1λ=1λ=RH[1n21−1n22]RH[1n12−1n22]

1λ=1λ=RH[122−132]RH[122−132]

⇒1.1×107[14−19]⇒1.1×107[14−19]

⇒1.1×107×536⇒1.1×107×536

λ=6.55×10−7mλ=6.55×10−7m

Now E=hcλE=hcλ

⇒6.62×10−34×3×1086.55×10−7⇒6.62×10−34×3×1086.55×10−7

⇒3.03×10−19J⇒3.03×10−19J

If N electrons show this transition in 1g atom of H then

Energy released=E×NE×N

⇒3.03×10−19×6.023×1023⇒3.03×10−19×6.023×1023

⇒18.25×104⇒18.25×104

⇒182.5KJ⇒182.5KJ

Hence (a) is the correct answer