Problem 3
Uranium can be separated from its daughter isotope thorium by dissolving a sample in acid and adding sodium iodide, which precipitates thorium(III) iodide: \(\mathrm{Th}^{3+}(\mathrm{aq})+3 \mathrm{I}^{-}(\mathrm{aq}) \rightarrow \mathrm{ThI}_{3}(\mathrm{~s})\) If \(0.567 \mathrm{~g}\) of \(\mathrm{Th}^{3+}\) were dissolved in solution, how many milliliters of \(0.500 \mathrm{M}\) NaI(aq) would have to be added to precipitate all the thorium?
Problem 3
How long does it take for 1.00 g of palladium- 103 to decay to 0.125 g if its half-life is 17.0 d?
Problem 3
How does a becquerel differ from a curie?
Problem 3
In the spontaneous fission of lead-208, the following reaction occurs: \({ }^{208} \mathrm{~Pb} \rightarrow{ }^{129} \mathrm{I}+{ }^{76} \mathrm{Cu}+3^{1} \mathrm{n}\) For every mole of lead-208 that decays, \(0.1002 \mathrm{~g}\) of mass is lost. How much energy is given off per mole of lead-208 reacted?
Problem 4
Thorium oxide can be dissolved in acidic solution: \(\mathrm{ThO}_{2}(\mathrm{~s})+4 \mathrm{H}^{+} \rightarrow \mathrm{Th}^{4+}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\ell)\) How many milliliters of \(1.55 \mathrm{M} \mathrm{HCl}(\mathrm{aq})\) are needed to dissolve \(10.65 \mathrm{~g}\) of \(\mathrm{ThO}_{2}\) ?
Problem 4
Name two isotopes that have been used in radioactive dating.
Problem 4
How long does it take for 2.00 g of niobium- 94 to decay to \(0.0625 \mathrm{~g}\) if its half-life is 20,000 y?
Problem 5
Describe an alpha particle. What nucleus is it equivalent to?
Problem 5
A sample of radon gas has an activity of \(140.0 \mathrm{mCi}\). If the half- life of radon is \(1,500 \mathrm{y}\), how long before the activity of the sample is \(8.75 \mathrm{mCi}\) ?
Problem 5
The current disintegration rate for carbon-14 is 14.0 Bq. A sample of burnt wood discovered in an archeological excavation is found to have a carbon-14 disintegration rate of \(3.5 \mathrm{~Bq}\). If the halflife of carbon- 14 is 5,730 y, approximately how old is the wood sample?
