The half-life of is 30.0 days. What fraction of a sample of this isotope will remain after 16.2 days?

[匿名]

2013-04-27 11:50 pm

a) The half-life of is 30.0 days. What fraction of a sample of this isotope will remain after 16.2 days?

b)he half-life of is 20.4 min. How long does it take for 2.20 g of the isotope to decay to 0.810 g?

c)Living organisms give a decay rate of 15.3 counts/min for each gram of carbon in the sample. A sample of wood from an Egyptian mummy case gave a count of 7.00 counts/min for each gram of carbon in the wood. How old was the mummy case? has a half-life of 5770 y.

d)How many grams of TiCl4 are needed to produce 17.8 g of titanium?

回答 (1)

Roger the Mole

2013-04-28 9:49 pm

✔ 最佳答案

a)
(1/2)^(16.2 / 30.0) = 0.688

b)
(1/2)^( z / 20.4) = (0.810 / 2.20)
Solve for z algebraically:
Take the log of both sides:
( z / 20.4) log (1/2) = log (0.810 / 2.20)
Divide by log (1/2):
( z / 20.4) = log (0.810 / 2.20) / log (1/2)
Multiply by 20.4:
z = 20.4 ( log (0.810 / 2.20) / log (1/2) ) = 29.4 min

d)
(17.8 g Ti) / (47.8671 g Ti/mol) x (1 mol TiCl4 / 1 mol Ti) x (189.6799 g TiCl4/mol) =
70.5 g TiCl4

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