# Ionization of the Sun

1. Jun 2, 2006

### Brewer

Question says:
Approximately how much energy would be required to ionize all the
hydrogen in the Sun? How does this ionization energy compare with
the thermal energy of the Sun?
(Assume the uniform density approximation. The ionization energy of
a single hydrogen atom is 2.18e−18 J.)

Am I to calculate the number of hydrogen atoms in the sun, and multiply by the ionization energy of a single atom? If so do you think its a decent assumption to say that the Sun is entirely made from hydrogen?

If so I get the ionization energy to be $$2.59*10^3^9 J$$ and the thermal energy to be $$1.47*10^3^8 J$$, so there isn't enough energy in the sun to ionise all its hydrogen

2. Jun 2, 2006

### Hootenanny

Staff Emeritus
If we consider the number of atoms, the sun is composed of about 91% hydrogen and the rest is mostly helium, so I would guess that it is a fair assumption.
Sounds good to me.

~H

3. Jun 2, 2006

### Brewer

Yippee!!! Intuition worked for once!

4. Jun 2, 2006

### Hootenanny

Staff Emeritus
Lmao. However, if you wish to be more accurate you could use the figures here; http://en.wikipedia.org/wiki/Sun to calculate actaully how much hydrogen is in the sun by mass then calculate the number of atoms and hence the ionisation enthalpy...

~H

5. Jun 2, 2006

### Andrew Mason

How do you get this value for the thermal energy?

AM