+0  
 
0
89
2
avatar

A radioactive element has a half-life of h years. In 500,000 years a given amount of this element would decay to 10% of its original amount. What is the half-life of this element? Thanks for help.

Guest Apr 2, 2017
Sort: 

2+0 Answers

 #1
avatar+25982 
+2

Use N/N0 = e^-(ln2*t/h)

 

0.1 = e^-(ln2*500000/h)

 

ln0.1 = -ln2*500000/h

 

h = -ln2*500000/ln0.1 ≈ 150515 years

.

Alan  Apr 2, 2017
edited by Alan  Apr 2, 2017
 #2
avatar
+1

Also, by this simple method:

 

0.1 = 2^-(500,000/h)

1/10 = 2^-(500,000/h) take the reciprocal of both sides,

10 = 2^(500,000/h)       take the log of both sides

500,000/h =log(10) / log(2)

500,000/h =3.321928...

h =500,000 / 3.321928

h ~ 150,515 years - the half-life of this element.

Guest Apr 2, 2017

11 Online Users

avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details