You are Here: Home

# Half life watch

1. I don't understand how to calculate the answer to this question: The half-life of one radioactive isotope is 71 days. By starting with 16g, calculate the mass of the remains that are left of this isotope after 213 days.
2. (Original post by Tayla1998)
I don't understand how to calculate the answer to this question: The half-life of one radioactive isotope is 71 days. By starting with 16g, calculate the mass of the remains that are left of this isotope after 213 days.
doesn't this mean every 71 days 1 half-life is completed i.e. the mass of the radioactive isotope is halved?
3. (Original post by Tayla1998)
I don't understand how to calculate the answer to this question: The half-life of one radioactive isotope is 71 days. By starting with 16g, calculate the mass of the remains that are left of this isotope after 213 days.
Three half lives have passed after 213 days (213/71 = 3)

After one half life 8g remains
After two half lives 4g remains
After three half lives 2g remains
4. (Original post by charco)
Three half lives have passed after 213 days (213/71 = 3)

After one half life 8g remains
After two half lives 4g remains
After three half lives 2g remains

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 10, 2016
The home of Results and Clearing

### 2,688

people online now

### 1,567,000

students helped last year
Today on TSR

### University open days

1. SAE Institute
Animation, Audio, Film, Games, Music, Business, Web Further education
Thu, 16 Aug '18
2. Bournemouth University
Fri, 17 Aug '18
3. University of Bolton