Energy Level Transitions of electrons?

Question

How much energy would be required to eject all the electrons from .10 mol of F ^(8+) in the n=2 state. Experess your answers in kJ

Answer 1

Fluorine F is the element in 2nd period and 7A group. neutral F atom only has 9 electrons. Thus, F^(8+) is a single-electron system, a hydrogen-like atom, whose energy level can be written as:
E = -R_h * Z^2 /n^2
where E is the energy for a single atom or ion, R_h = 13.6eV or = 2.179×10^-18 J, Z is the atomic number: Z = 9 for F^(8+), and n the principle quantum number.
The problem is not clear whether to eject all the electrons to other state (different n), or to eject the electrons to infinity (to further ionize F(8+)). Let us assume the later is asked. Hence the energy required is:
E(total) = (0.10mol)*(6.022x10^23/mol)*(2.179×10^-18 J)* 9^2 /2^2
= 2.657x10^3 kJ.