Unlike chemical reactions, for which mass is conserved, nuclear reactions result

Question

Unlike chemical reactions, for which mass is conserved, nuclear reactions result in slight changes in mass. When mass is lost, it becomes energy according to the equation ALE Am where AE is the energy in joules, Am is the mass defect in kilograms, and c is the speed of light (c 33.00 x 108 m/s). The mass defect is the difference between the total mass of the products and the total mass of reactants. The following values can be used to calculate the mass defect. Mass Particle (g/mol) Ae 0.00054858 1.00782 He 4.00260 Part A The sun produces energy via fusion. One of the fusion reactions that occurs in the sun is 4 H He 2 e How much energy in joules is released by the fusion of 1.80 g of hydrogen-1? Express your answer to three significant figures and include the appropriate units AE Value Units Submit Hints My Answers Give Up Review Part

Explanation / Answer

mass defect = mass of products - mass of reactants

                          = (mass of He   + mass of electron)   - ( 4 x mass of H)

                           = (4.00260 + 2X0.000548) - (4X1.00782) = 4.003696 - 4.03128 = -0.027584 g

The energy given off then can be calculated using

        energy = mass defect x speed of light 2

Energy = -0.027584 X 10^-3 X 3X10^8 X 3X10^8 = 0.248X10^13 Joules

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