Posted by **Eddy** on Monday, April 25, 2011 at 2:33pm.

A 1.00-g sample of carbon from a modern

source gave 15.3 disintegrations per minute. A sample of carbon from an “old” source gave 920 disintegrations per hour. What is the age of the “old” sample of carbon? The half-life of carbon-14 is 5.73×103 year.

a. about 34,400 years

b. about 345,000 years

c. about 20 million years

d. less than a few years

- chemistry -
**Eddy**, Monday, April 25, 2011 at 2:34pm
Typo: The half-life is 5.7x10^3

- chemistry -
**drake**, Monday, April 25, 2011 at 5:11pm
Without even doing the math it the change in disintegrations is merely .03333, the sample must have decayed for

d. less than a few years

- chemistry -
**drake**, Monday, April 25, 2011 at 5:16pm
whoops, i did the math and it came out to about 34,400 years. Sorry for my earlier answer

- chemistry--can't get 34,000 yrs -
**DrBob222**, Monday, April 25, 2011 at 6:28pm
k = 0.693/t_{1/2}

k = 0.693/5.7E3 = 1.22E-4

ln(15.3333/15.3) = 1.22E-4(t)

t = about 18 year.

- chemistry -
**Anonymous**, Monday, April 25, 2011 at 11:39pm
vanden bout

- chemistry -
**mayra**, Tuesday, October 15, 2013 at 3:07pm
actually drake was right on his first answer i had this question on my homework and it is d. less than a few years :)

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