chem
posted by sarah .
The halflife of is 30.0 days. What fraction of a sample of this isotope will remain after 16.2 days?

chem 
jimbo
after 30 days 50% of the sample would have decayed. 50% / 30 days gives you a daily decay rate of 1.6666667. multiply this by 16.2 to give 27. 27 is the percentage of the sample that has decayed after 16.2 days so 10027 = 73%

chem 
DrBob222
I don't believe that 1.6667 is a constant. For example, at the end of another 30 days it shows 50% and that + te 50 already gone is now zero remaining when in fact there is 25% remaining after 60 days.
k = 0.693/t_{1/2}. Solve for k and substitute into the equation below.
ln(No/N) = kt
No = 100%
N = % remaining
k from above
t = 16.5 days.
Solve for N.
Respond to this Question
Similar Questions

chemistry
How do you find the halflife of an element? 
chemistry
Ba140 has a half life of 13.0 days. What fraction of a sample will remain after 39 days? 
Chemistry
Ba140 has a half life of 13.0 days. What fraction of a sample of Ba140 will remain after 39 days? 
Chemistry
What is used to tell different isotopes of a particular element apart? 
Physics 30
The activity of a sample of a radioactive isotope is 1800Bq. If this isotope has a halflife of 16 days, what is the activity after 16 days? 
chemistry
A radioactive sample contains 2.45g of an isotope wiht a half life of 3.8 days. How much of the isotope in grams remains after 11.4 days? 
chemistry
A radioactive sample contains 2.45 g of an isotope with a halflife of 3.8 days. How much of the isotope in grams will remain after 11.4 days? 
PreCalc
A radioactive isotope has a half life of 8.1 days. If the sample starts with 25 grams, how much will there be after 90 days? 
chemistry
The radioactive isotope, phosphorus32, has a halflife of 14.26 days. How much phosphorus32 will remain after 60 days? 
chemistry
Examine the information. Isotope B has a halflife of 3 days. A scientist measures out 100 grams of this substance. After 6 days has passed, the scientist reexamines the sample. How much of Isotope B will remain in the sample?