HARDMCQ SINGLENEET ChemistryPhysical ChemistryAtomic StructureIntro
When sodium compounds are heated in a Bunsen burner flame, they emit light at 5890 Å. If 1.0 × 10⁻⁴ moles of sodium atoms each emit one photon of this wavelength, how much energy (in kJ) is emitted?
0.2.03 × 10⁻² kJ
1.8.08 × 10⁻³ kJ
2.6.20 × 10⁻² kJ
3.2.03 × 10⁻³ kJ
Explanation
n = 10⁻⁴ × 6.023×10²³ = 6.023×10¹⁹ atoms. E = nhc/λ = (6.023×10¹⁹ × 6.626×10⁻³⁴ × 3×10⁸) / (5890×10⁻¹⁰) = 0.02031 kJ = 2.03×10⁻² kJ
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