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 lire equation Delta E = delta m middot c^2 where Delta E is the energy in joules, Delta m is the mass defect in kilograms, and c is the speed of light (c = 3.00 Times 10^8 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. The sun produces energy via fusion. One of the fusion reactions that occurs in the sun is 4^1_1H rightarrow_2^4He + 2_1^0e How much energy in joules is released by the fusion of 1.90 g of hydrogen-1? Express your answer to three significant figures and include the appropriate units.

Explanation / Answer

Number of moles of 1H1 = 1.9/1.00782

=1.885257 moles

number of moles of 4H2 = 1.885257/4

=0.471314

number of moles of e = 2*1.885257

=3.770514

so mass defect = 1.9 - 0.471314*4.0026 - 3.770514*2*0.00054858

=0.0093817

so dE=mc^2

=0.00938*9*10^16

=8.442*10^14 J

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