David kept 100 grams of radioactive sodium in a container. He observed the amount of sodium left in the container after regular
2 answers:
Answer: A. The half life period of radioactive sodium is 15 hours.
Explanation:
Half life is the time taken by a reactant to reduce to its original concentration. It is designated by the symbol .
Given:
At 0 hours the amount of sodium in container is 100 grams
After 15 hours , the amount of sodium in container is 50 grams which is half of the original amount of 100 grams.
It will take 15 hours for half of a 100 g sample to decay to half of the amount i.e. 50 grams.
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Answer:
1,812 wt%
Explanation:
The reactions for this titration are:
2Ce⁴⁺ + 3I⁻ → 2Ce³⁺ + I₃⁻
I₃⁻ + 2S₂O₃⁻ → 3I⁻ + S₄O₆²⁻
The moles in the end point of S₂O₃⁻ are:
0,01302L×0,03428M Na₂S₂O₃ = 4,463x10⁻⁴ moles of S₂O₃⁻. As 2 moles of S₂O₃⁻ react with 1 mole of I₃⁻, the moles of I₃⁻ are:
4,463x10⁻⁴ moles of S₂O₃⁻× = 2,2315x10⁻⁴ moles of I₃⁻
As 2 moles of Ce⁴⁺ produce 1 mole of I₃⁻, the moles of Ce⁴⁺ are:
2,2315x10⁻⁴ moles of I₃⁻× = 4,463x10⁻⁴ moles of Ce(IV). These moles are:
4,463x10⁻⁴ moles of Ce(IV)× = <em>0,0625 g of Ce(IV)</em>
As the sample has a 3,452g, the weight percent is:
0,0625g of Ce(IV) / 3,452g × 100 = <em>1,812 wt%</em>
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