# Original Sample of Nuclides

Please see the attachment for the questions, which are chemistry questions related to finding a compound's half-life, balancing equations, etc. Please show the steps involved with solving these problems.

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## SOLUTION This solution is **FREE** courtesy of BrainMass!

Please find answers to your questions attached. Please confirm if the isotope of Calcium in question 12 is Ca-45. If so, then the calculated value agrees with the literature value.

11. The equation for radioactive decay is NT = N0 Ã— eâˆ’kt

Where NT is the Amount remaining after a time t (minutes) and k is the radioactive decay constant

Taking the logarithm of both sides with respect to e, you can rewrite the equation as

ln (N_32/N_0) = kÃ—T1/2

and from which we get ln (0.5) = k Ã— 32.....................................................(1)

since 32 minutes is the half-life

Then we also have ln (N_180/N_0) = kÃ—180....................................................(2)

Where we need to find N_180/N_0 where N180 refers to the amount left after 180 minutes or 3 hours.

Dividing (2) by (1) we get ln ln (N_180/N_0) = 180 Ã— 32 Ã— (ln 5) = -3.899

Which gives (N_180/N_0) = 0.02026

OR only 2.03% of the original amount is left after 180 min or 3 hours.

12. Using the same equation for radioactive decay

ln (N_t/N_0) = âˆ’kÃ—t

where k is the decay constant and t is the time

For the half-life, N_t/N_0 = 0.5 and k = 4.23 Ã— 10âˆ’3 dayâˆ’1

And t1/2 = ln 0.5/4.23 Ã— 10âˆ’3 dayâˆ’1 = 163.86 days for the 45-Ca isotope.

13. PCl3 + 3H2O â†’ H3PO3 + 3HCl

14. P4O10 + 6H2O â†’ 4H3PO4

15.

[Co(NH3)4Cl2]Br

Tetraamminedichlorocobalt(III) bromide

16. Coordination of Cobalt(III) = 6

17. Coordination Geometry = Octahedral, or more correctly, distorted Octahedral.

18. Geometrical iosmerism may be exhibited by this complexâ€”the two Cl ligands may be trans (opposite) to each other OR the two Cl ligands may be cis to each other (adjacent)

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