# Homework Help: Binding Energy for Hydrogen

1. Sep 8, 2009

### burg25

1. The problem statement, all variables and given/known data
Find the binding energy for hydrogen in kJ/mol through positron emission.

4(11H) → 42He + 2(0+1ß)

2. Relevant equations
E=Δmc2
Mass of Hydrogen: 1.0079 amu
Mass of Helium: 4.0026 amu
1 amu = 1.6605 x 10-27kg

3. The attempt at a solution
Here is what I did:

Eb= ((number of protons)xmass hydrogen)-mass of helium)*1.6605x10-27kg/amu)*c^2
Eb = ((4*1.0079 - 4.0026) * 1.6605*10-27)*(2.998x108)2
Eb= 4.33x10-12 kg m2/s2 = 4.33x10-12 J
Eb = 4.33 x 10-15 kJ
Eb = 4.33 x 10-15 * 6.022 x1023
Eb = 2.61 x 109 kJ/mol
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 9, 2009

### chemisttree

Haven't you neglected the mass of the 2 positrons?

In the equation, E=Δmc2, the Δm = mass of reactants - mass of all products (including positrons)

3. Sep 9, 2009

### burg25

Isn't a positron basically massless considering it would just have the mass of an electron or will it make a big difference?