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STatiana [176]
2 years ago
7

Uranium-238 decays very slowly.its half-life is 4.47 billion years.

Chemistry
2 answers:
aleksandrvk [35]2 years ago
7 0

Answer:

12.53 % of a sample of Uranium-238 will remain after 13.4 billion years.

Explanation:

The half life of the uranium-238 = t_{\frac{1}{2}}=4.47 billion years

All the radioactive reaction are of first order kinetics. The rate constant and t half of the reaction are related as:

k=\frac{0.693}{t_{\frac{1}{2}}}=\frac{0.693}{4.47 \text{billion years}}=0.1550 (\text{billion years})^{-1}

k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}

where,  

k = rate constant = 0.1550 (\text{billion years})^{-1}

t = time taken during radio decay  = 4.47 billion years

[A_o] = initial amount of the reactant = 1.45\times 10^{-6}mol/L

[A] = amount left left after time t.

\log \frac{[A]}{[A_o]}=-\frac{kt}{2.303}

\frac{[A]}{[A_o]}=0.1253=\frac{12.53}{100}=12.53\%

12.53 % of a sample of Uranium-238 will remain after 13.4 billion years.

coldgirl [10]2 years ago
6 0
13.4 billion years is 3 times of the half-life, 4.47 billion years. So the Uranium-238 will go through three times of half decay. So the remain percentage will be 50%*50%*50%=12.5%.
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