Question

Pre-Laboratory Questions 1. An emission line of sodium has a wavel emitted in J/atom, and the energy emitte ne of sodium has a wavelength of 300 m. Calculate the energy of a photo of light atom, and the energy emitted per mole of Na atoms in kl/mol at this wavelength. 2. Determine the corresponding emission wavelength (in nm) for the emission energies (in kJ/mol of each Group IA or IIA metal given in the table below. Wavelength (nm) Element Emission Energy (kJ/mol 178.2 203.5 155.3 156.5 184.8 198.7 191.4 216.1 178.2 197.5 144.5 161.9

Answer 1

Q1. Wavelength = 330 nm = 330 x 10^-9 m

energy of atom = [(Planck's constant) * (speed of light)] / (wavelength)

energy of atom = [(6.626 x 10^-34 J.s) * (3.0 x 10⁸ m/s)] / (330 x 10^-9 m)

energy of atom = 6.02 x 10^-19 J

energy of 1 mole of Na atoms = (energy of atom) * (Avogadro's number)

energy of 1 mole of Na atoms = (6.02 x 10^-19 J/atom) * (6.022 x 10²³ atoms/mol)

energy of 1 mole of Na atoms = 362743.4 J

energy of 1 mole of Na atoms = 362.7 kJ/mol

Q2.

Element	Emission Energy (kJ/mol)	Wavelength (nm)
Li	178.2	671.7
Na	203.5	588.2
K	155.3	770.8
	156.5	764.9
Ca	184.8	647.8
	198.7	602.4
	191.4	625.4
	216.1	553.9
Sr	178.2	671.7
	197.5	606.1
Ba	144.5	828.4
	161.9	739.4