Thursday

October 2, 2014

October 2, 2014

Posted by **marjani** on Saturday, August 27, 2011 at 9:00am.

- chemistry -
**DrBob222**, Saturday, August 27, 2011 at 1:59pmThis is the long way but I would do this.

ln(No/N) = kt

Substitute

No = 100 (just make up any number)

N = 25 (25% of whatever you picked for No)

k = solve for this

t = 40 minutes.

Then substitute k into

k = 0.693/t_{1/2}and solve for t_{1/2}.

**Answer this Question**

**Related Questions**

chemistry - a radioactive material is undergoin nuclear decay. After 40 minutes...

chemistry - use the nuclear decay equation to find out how much a 7mg sample of ...

Science- Radioactive Dating - Which of the following statements about ...

chemistry - How long will it take for 25% of the C-14 atoms in a sample of C-14 ...

Algebra 2 help... - A half life of a certain radioactive is 36 days. An initial ...

chemistry - If there are 80 milligrams of a radioactive element decays to 10 ...

calculus - The rate at which an amount of a radioactive substance decays is ...

math - An unknown radioactive element decays into non-radioactive substances. In...

math30 - The mass of a radioactive sample is represented in the graph below. The...

Algebra I - A sample of radioactive material weighing 45 grams has a decay rate ...