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For planck’s photon energy equation when calculating wavelength it makes no sense for it to be negative.

The answer I get is negative because the energy value is the only negative variable, heat is given out so it’s said that the reaction is exothermic heat taken in is positive.

Units:

$h=6.262\cdot 10^{-34}\ j\cdot s^{-1}$

$c=2.998\cdot 10^{8}\ m\cdot s^{—1}$

${NA}=6.022\cdot 10^{23}\ mol^{-1}$

$E=-533000\ j\cdot mol^{-1}$

$\lambda=x\cdot m$

$$ \lambda=\frac{h\cdot c\cdot {NA}}{E}=\frac{h\cdot c}{E} $$

$$ \lambda=\frac{(6.626\cdot 10^{-34})(2.998\cdot 10^{8})(6.022\cdot10^{23})}{(-533000)}=-224nm $$

Obviously the length can’t be negative so I just so I just put it as positive, but is there a mathematical technique for situations like this? I’m just trying to learn.

Nickotine
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    All of those numbers are positive. I suspect your error is in using our calculator. – John Douma Mar 27 '21 at 16:05
  • damn the denominator was meant to be negative @johndouma I edited – Nickotine Mar 27 '21 at 16:10
  • @Nickotine How come the value of $;j\cdot mol;$ is negative ? – DonAntonio Mar 27 '21 at 16:12
  • This isn't really a math question (certainly not a linear-algebra question). Maybe the Physics StackExchange would be a better place for it. – Blue Mar 27 '21 at 16:12
  • it’s just how do I mathematically deal with this wrong negative value? @blue not sure what to tag this as – Nickotine Mar 27 '21 at 16:12
  • because: $$bondBreakEnergy=bondEnergyReactants-bondEnergyProducts$$ where the products have a higher bond energy value @donantonio – Nickotine Mar 27 '21 at 16:15
  • @Nickotine: Whether a negative value of a physics-oriented calculation has a valid interpretation is a question for physicists. (As for tagging ... Maybe soft-question?) – Blue Mar 27 '21 at 16:18
  • Photons cannot have negative energy. – Zadig Mar 27 '21 at 16:20
  • @blue changed it but is there even a mathematical situation where you have to deal with an expected negative? – Nickotine Mar 27 '21 at 16:20
  • this is like when a physicist says a ball has a positive speed value when going up and a negative value when going down, I thought they got this from maths? – Nickotine Mar 27 '21 at 16:23
  • @Nickotine: Mathematically, if I multiply and/or divide an odd number of negative values, I expect to get a negative result. I personally can't speak to what's expected scientifically here. – Blue Mar 27 '21 at 16:24
  • @blue I thought science got all their stuff from you guys, mathematicians? – Nickotine Mar 27 '21 at 16:26
  • @Nickotine: Comments aren't for discussion. I have nothing more to contribute here. Good luck to you! :) – Blue Mar 27 '21 at 16:28
  • sorry posting this here shall I just delete it or can it be moved? – Nickotine Mar 27 '21 at 16:35

1 Answers1

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Just make one of the other values negative as well, for example, let $c=-2.998\cdot 10^{8}\ m\cdot s^{—1}$. Then you get a positive length.

JMP
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