I’ve been reading about HL, but I still don’t get why would you use it. So, if half life of coffee is 5h, how that info is relevant when we know that full life is 10 (roughly)? On top of that, how do you get the half-life of a material other than waiting to be completely ‘dead’ and say, ok full life is X, the half life is X/2.
Also, let’s take uranium which in Earth’s crust has a half-life of almost 4.5 billion years.. how did we get this number?
Thank you!
In: Chemistry
Full life is not half life x 2. Full life is in theory infinity, in pratice the last decay happens at some discrete point but you cant predict when it happens. For coffee with a half life of 5 hours after 10 hours not 100% is gone but 75%. Not half of the original amount decay after half live but half of the current amount. So if you start out with 100 of something with a half live of 5h after 5h you have 50. After 10h you have 25. After 15h you have 12 or 13. After 20 you have 6-8 and so on.
For Uranium you just take something like a kg of it and wait for a day to detect how much decayed. You can then say it would take x billion years for half to decay.
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