Question #4ce19

1 Answer
Mark C.
Nov 9, 2017

I can certainly help with the early part of this question.

Explanation:

Planck’s equation states that #E = h.f# and as #c = f.lambda# we can find the wavelength:

#f = E/h =( 2.961xx10^-19) /( 6.63xx10^-34)#

#f = 4.47xx10^14# Hz

#lambda = c/f = (3xx10^8)/(4.47xx10^14 #

#lambda = 6.71xx10^-7# m

ThIs is a deep red colour, which makes sense - lithium ions in a flame test show red.

The total energy of one mole is more tricky, it relies on the assumption that all the ions emit light simultaneously, which given quantum theory’s inherent probabilistic nature seems unlikely, but still ...

#N_A = 6.023xx10^23# so we multiply the energy of one emission by this to get the total energy.

#E = 1.78xx10^5# J

... this is a lot of energy.

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