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kirill115 [55]
4 years ago
14

If 50% of a radioactive element remains after 4000 years, what is the half-life?

Chemistry
1 answer:
ANTONII [103]4 years ago
4 0

Hey there!

A half-life means after a certain amount of time, half of that substance will be gone/changed after that time.

If 50%, or half, of the element remains after 4000 years, that means the half life must be 4000 years.

Hope this helps!

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When F⁻ is added, CaF₂ and BaF₂ are produced following the ksp equation:

For CaF₂:

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Ksp = 1.5x10⁻⁶ = [Ba²⁺] [F⁻]²

<em>Where [Ba²⁺] = 0.090M * {25mL / (25mL + 35mL)} = 0.0375M</em>

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[F⁻]² = 4x10⁻⁵

[F⁻] = 6.3x10⁻³M

BaF₂ begins precipitation when [F⁻] = 6.3x10⁻³M

Thus, the fluoride which precipitates first is CaF₂

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