Finding the binding energy for lithium

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SUMMARY

The binding energy for lithium-8 (3Li8) is calculated using the formula: Binding energy = (#p)(mass proton) + (#n)(mass neutron) - (mass nuclei*c^2). The atomic mass of lithium-8 is 8.022486 u, with the mass of a proton being 1.007825 u and a neutron 1.008665 u. The calculated binding energy yields a negative value of -4.506e30 MeV, indicating a miscalculation in unit conversion or formula application. It is crucial to ensure consistent units, particularly when using c = 3 x 10^8 m/s, which necessitates converting atomic masses to kilograms.

PREREQUISITES
  • Understanding of nuclear physics concepts, specifically binding energy.
  • Familiarity with atomic mass units (amu) and their conversions.
  • Knowledge of unit conversion between joules and electronvolts (eV).
  • Basic proficiency in algebra for manipulating equations.
NEXT STEPS
  • Review the principles of nuclear binding energy calculations.
  • Study unit conversion techniques between atomic mass units and kilograms.
  • Learn about the implications of negative binding energy values.
  • Explore the significance of using consistent units in physics equations.
USEFUL FOR

Students studying nuclear physics, educators teaching binding energy concepts, and anyone involved in atomic mass calculations.

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Homework Statement


Find the binding energy (in MeV) for lithium 3Li8 (atomic mass = 8.022486 u).


Homework Equations


Binding energy = (#p)(mass proton) + (#n)(mass neutron) - (mass nuclei*c^2)


The Attempt at a Solution


mass proton = 1.007825
mass neutron = 1.008665
Binding energy = (3)(1.007825) + (5)(1.008665) - (8.022486*(3e8)^2)
Binding energy = -7.22e17 J x 1 eV/1.602e-19 J = -4.506e36 eV x 1e-6 MeV / 1 eV = -4.506e30 MeV
 
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Check your units please. Also your formula for binding energy is wrong. Check the c2's.
 
Oops, sorry I know I typed the formula wrong on here, but I did it the correct way on my homework... It's still telling me my answer is incorrect. :/
 
mass proton = 1.007825
mass neutron = 1.008665

are atomic mass units (amu). Be careful about mixing units.

If one is using c = 3 x 108 m/s, then one must use atomic masses in kgs.
 

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