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Musya8 [376]
3 years ago
5

The half-life of thorium-227 is 18.72 days. How many days are required for three-fourths of a given amount to decay?

Chemistry
1 answer:
Pie3 years ago
7 0
T½=18.72days
therefore t¾=18.72+½ of 18.72
we have 18.72+9.36=28.08days
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Answer:

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Explanation:

Enthalpy change for a reaction,  is given as:

\Delta H_{rxn}=\sum [n_{i}\times (E_{bond})_{i}]-\sum [n_{j}\times (E_{bond})_{j}]

Where (E_{bond})_{i}  and (E_{bond})_{j} represents average bond energy in breaking "i" th bond and forming "j" th bond respectively.n_{i} and n_{j} are number of moles of bond break and form respectively.

In this reaction, one mol of C=C, four moles of C-H and one mol of F-F bonds are broken. One mol of C-C bond, four moles of C-H bonds and two moles of C-F bonds are formed

So, -549kJ=(1mol\times 614kJ/mo)+(4mol\times E_{C-H})+(1mol\times 154kJ/mol)-(1mol\times 347kJ/mol)-(4mol\times E_{C-H})-(2mol\times E_{C-F})

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or, E_{C-F}=485kJ/mol

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