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23 Nov 2019

Nuclear reactors generate power by harnessing the energy fromnuclear fission. In a fission reaction, uranium-235 absorbs aneutron, bringing it into a highly unstable state as uranium-236.This state almost immediately breaks apart into two smallerfragments, releasing energy. One typical reaction is

^{235} _{\ 92} {\rm U} + ^{1}_{0}{\rm n} \rightarrow \ ^{140} _{\54} {\rm Xe} + ^{94} _{38} {\rm Sr} + 2^{1} _{0} {\rm n},
where ^{1} _{0} {\rm n} indicates a neutron. In this problem,assume that all fission reactions are of this kind. In fact, manydifferent fission reactions go on inside a reactor, but all havesimilar reaction energies, so it is reasonable to calculate withjust one. The products of this reaction are unstable and decayshortly after fission, releasing more energy. In this problem, youwill ignore the extra energy contributed by these secondarydecays.

You will need the following mass data:

* mass of ^{235} _{\ 92} {\rm U} = 235.04393\;{\rm u},
* mass of ^{140} _{\ 54} {\rm Xe} = 139.92144\;{\rm u},
* mass of ^{94} _{38} {\rm Sr} = 93.91523\;{\rm u}, and
* mass of ^{1} _{0} {\rm n} = 1.008665\;{\rm u}.

a. What is the reaction energy Q of this reaction? Use c^2 =931.5\; {\rm MeV/u}.
Express your answer in millions of electron volts to threesignificant figures.
Q =


{\rm MeV}


Part B
Using fission, what mass m of uranium-235 would be necessary tosupply all of the energy that the United States uses in a year,roughly 1.0 \times 10^{19}\; {\rm J}?
Express your answer in kilograms to two significant figures.
m =


{\rm kg}



Please answer fully.... thank you

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Beverley Smith
Beverley SmithLv2
23 Nov 2019
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