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# Mass Defect and Energy Released from Nuclear Waste

CHEM-YPASMF

Thirty years ago, a large amount of Caesium-137 was released into the environment during the nuclear accident at Chernobyl. The contamination of the radioactive isotope due to this accident was the greatest risk to health in all major European countries. Radioactive decay of Caesium into Barium takes place by the release of $\beta$ particles.

$$_{ 55 }^{ 137 }{ Cs }\longrightarrow _{ 56 }^{ 137 }{ Ba } + _{ -1 }^{ 0 }{ \beta } \quad \quad { t }_{ 1/2 }^{ } = 30.17 \ \text{ years}$$

What is the mass defect (in kg) and the energy released (joules) from the decay of $\beta$ particles by $_{ 55 }^{ 137 }{ Cs } ?$

Keep in mind the following numbers:

• The mass of $(_{ 55 }^{ 137 }{ Cs })$ = 136.907089 amu (atomic mass units)
• The mass of $(_{ 56 }^{ 137 }{ Ba })$ = 136.905812
• The mass of an electron (beta particle) = ${ 5.485 \times 10 }^{ -4 }$ amu
• Avagadro's number = ${ 6.023 \times 10 }^{23}​$ amu
• $c$ = $3.00 \times { 10 }^{ 8 } { m/s }$
A

$+1.209 \times { 10 }^{ -30 } kg$ and $+1.088 \times { 10 }^{ -14 }J$

B

$+1.209 \times { 10 }^{ -27 } kg$ and $+1.088 \times { 10 }^{ -11 }J$

C

$-1.209 \times { 10 }^{ -27 } kg$ and $-1.088 \times { 10 }^{ -11 }J$

D

$-1.209 \times { 10 }^{ -30 } kg$ and $-1.088 \times { 10 }^{ -14 }J$