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olchik [2.2K]
3 years ago
8

There is a 50 g sample of ra-229. It has a half-life of 4 minutes.how much will be left after 12 minutes? a. 3.13 g b. 6.25 g c.

12.5 g d. 25 g
Chemistry
1 answer:
polet [3.4K]3 years ago
3 0

It's B. 6.25

first divide 50/2

then divide 25/2

after that divide 12.5/2

Then you get 6.25

Hope it helps!

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Cyclopropene decomposes to propene when heated to 500 C, calculate rate constant for the first order reaction 0 min 1.48 mmol/L
Dmitry_Shevchenko [17]

Answer:

k = 0.0306 min-1

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Time, Concentration

0 1.48

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10 0.98

15 0.84

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ln [A] = -kt + ln [Ao]

where;

[A] = Final Concentration

[Ao] = Initial Concentration

k = rate constant

t = time

In the table, taking the first two sets of values;

t = 5

k = ?

[Ao]  = 1.48

[A] = 1.27

Inserting into the equation;

ln(1.27) = - k (5) + ln(1.48)

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8 0
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