The half-life for the radioactive decay of iridium-192 is 74.2 days. calculate the amount in grams of ir-192 that will be left from a 13.65g sample after a) 199.2 days b) 350 days

There are

a) 2.12 g of Ir-192 after 199.2 days

b) 0.52 g of Ir-192 after 350 days

Explanation:

Radioactive decay follows a first-order kinetics since the half life does not depend on the initial amount, then the equation which describes this process is:

Where is the amount given a certain t time, and is the initial amount. is the half life.

Then, the radioactive decay equation for this problem is:

Note that the half life and the given time t must be on the same units, in this case days. Finally you calculate the amount for a) 199.2 days and b) 350 days:

Hope it helps!

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