Determine the rate constant for an isotope disintegrating to 1/8 th of its origi

[Mamona]

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Determine the rate constant for an isotope disintegrating to 1/8 th of its original sample in 9 years.

Answer : 0.231 years

I don't understand the answer to this problem, and I don't know how to do it either. I though I had half-life rxn clear but this one mess me up!!!!

Thanks

 

[tranv117]

#half lives = ln2/decay constant. Asking for decay constant so ln2/#half life. 1/8th of the original means that it has gone through 3 half lives. therefore ln2/3 equals. .231 decay constant.

This is just an equation you must know for half lives.

 

[tranv117]

im sure you were probably just thinking about the time if takes to decay to 1/8th of its sample given a certain number or years...

 

[Mamona]

im sure you were probably just thinking about the time if takes to decay to 1/8th of its sample given a certain number or years...

Yes that was exactly what I was thinking!!! Thank you very much

 

[Mamona]

How do you calculate ln without a calculator????

 

[aquafreshlovin]

Just memorize this: ln2 = 0.693

🙂

 

[EKdental09]

#half lives = ln2/decay constant. Asking for decay constant so ln2/#half life. 1/8th of the original means that it has gone through 3 half lives. therefore ln2/3 equals. .231 decay constant.

This is just an equation you must know for half lives.

I read through how to do this calculation but didn't focus on it much because I figured they wouldn't make us do that complicated of a calculation.. (or maybe its not that complicated and I'm just bad at math).. can someone explain how you calculate it?