If you were a scientist working on the development of nuclear fusion reactions you would have to know how much energy is stored in a nucleus as its binding energy. Calculate the nuclear binding energy in electronvolts of a helium-4 nucleus, given the following masses: ⁴He, 4.0026m_u; ¹H, 1.0078m_u; n, 1.0087m_u, with mu the atomic mass constant (1.660 54 * 10^–27 kg).

ANTICIPATE Because nuclear reactions can release huge amounts of energy, you should expect a large value for the nuclear binding energy.

PLAN Write the nuclear equation for the formation of the nuclide from hydrogen atoms and neutrons, and calculate the difference in masses between the products and the reactants (H atoms are used instead of protons to account for the mass of the electrons in the He atom); convert the result from a multiple of the atomic mass constant into kilograms. Then, use the Einstein relation to calculate the energy corresponding to this loss of mass and convert the units to electronvolts.