Energy required to ionize a hydrogen atom from n=1

[tony873004]

We were given this formula in class:

delta E= chR (\frac{1}{1^2} - \frac{1}{inf})

the 1/1^2 is because it is in ground state. So the formula simplifies to
chR

c = 299792000
h = 6.626E-34
R = 10970000

and 1.60217653*10^{19} Joules / eV

I get:
1.36009026784583 * 10^{-37} eV

The teacher did it in class and got 13.6 eV

Same answer, just 38 magnitudes off

What am I doing wrong?

** edit ** I figured it out. It's not 19, its -19 for Joules to eV

 

[dextercioby]

There you go:you have scientifically proven that 10^{-19} and 10^{19} are 38 orders of magnitude apart.Congratulations!

Daniel.

 

[wais]

It seems like you have made a small error in your calculations. The correct conversion factor from Joules to eV is 1.60217653*10^-19 (negative exponent). When you use the correct conversion factor, you will get the same answer as your teacher, 13.6 eV. It's important to pay attention to the units and their exponents in calculations like this to avoid errors. Keep up the good work!