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likoan [24]
3 years ago
9

The half life for the decay of carbon-14 is 5.73 x 10 years. Suppose the activity due to the radioactive decay of the carbon-14

in a tiny sample of an artifact made of wood from an archeological dig is measured to be 19. Bq. The activity in a similar-sized sample of fresh wood is measured to be 20. Bq. Calculate the age of the artifact. Round your answer to 2 significant digits. years X 5 ?
Chemistry
1 answer:
Elena-2011 [213]3 years ago
6 0

Answer:

Age of the atifact is 4.2\times 10^{2} years

Explanation:

  • For first -order radioactive decay- A_{t}=A_{0}(\frac{1}{2})^{\frac{t}{t_{\frac{1}{2}}}}
  • A_{t} represents activity of radioactive nuclide after t time, A_{0} represents initial activity of radioactive nuclide and t_{\frac{1}{2}} represents half-life
  • Here, A_{t}=19Bq, A_{0}=20Bq and t_{\frac{1}{2}}=5.73\times 10^{3}years

Plug-in all the given values in the above equation-

19=20\times (\frac{1}{2})^{\frac{t}{5.73\times 10^{3}}}

or, t=4.2\times 10^{2}

So, age of the atifact is 4.2\times 10^{2} years

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Answer:

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Answer:

lattice parameter = 5.3355x10^-8 cm

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Explanation:

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p=0.855 g/cm^3

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Avogadro number = 6.02x10^23 atom/mol

a) the lattice parameter:

Since potassium has a cubic structure, its volume is equal to:

v = [(atoms/cell)x(atomic mass)/(p)x(Avogadro number)]

substituting values:

v =[(2)x(39.09)/(0.855x6.02x10^23)]=1.5189x10^-22 cm^3

but as the cell volume is

a^3 =v

a=\sqrt[3]{v}=\sqrt[3]{1.5189x10^{-22} } = 5.3355x10^-8 cm

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r=\frac{ax\sqrt{3} }{4}=\frac{5.3355x10^{-8}x\sqrt{3}  }{4}=2.3103x10^{-8}cm

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2 years ago
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Answer:

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Like molecular formulas, empirical formulas are not unique and can describe a number of different chemical structures or isomers. <u>To determine an empirical formula, the relative molecular mass of the composition of its elements</u> can be used to mathematically determine their ratio.

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Medical cold packs can use various chemicals in order to produce a cold compress to help reduce inflammation caused by injuries.
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Answer:

Mass of KCL = 218 grams.

Explanation:

Step 1: calculate the heat that must be absorbed(q).

Heat that must be absorbed(q) is calculated as follows:

q= m c (T2-T1).

q = 750g (4.18 J/gC)(20-4 C) = 5.016X10^4 J = 50.16 kJ

Step 2: we determine moles of KCL as follows:

Moles KCl = 50.16 kJ / 17.2 kJ/mol = 2.92 moles.

Step 3: calculate mass of KCL:

Mass of KCl = 2.92 mol X 74.55 g/mol = 218g.

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