00:01
Okay, so in this question, they want us to calculate how many disintegrations per second or occur in 1 milligram of iodine 129.
00:10
So we have 1 milligram of iodine 129, and they tell us that the half -life is 1 .7 times 10 to 7 years.
00:27
So the first thing we have to do is find the decay constant.
00:30
So the equation is t half -life equal to 0 .693 over lambda, which is a decay constant.
00:39
Now let's get decay constant by itself.
00:41
So we multiply lambda on both sides.
00:45
We would get lambda t -half -life equals 0 .693.
00:50
Now we divide by the half -life, and we isolate a lambda or the decay constant.
00:58
Now let's plug in the values.
00:59
We have the decay constant equals 0 .693.
01:04
Over 1 .7 times 10 to 7 years right but what we want to do is we want to convert the years into seconds right so how would we do that so all we got to do is right one year has 365 days right so one day has 24 hours one hour has 60 minutes and one minute has 60 seconds right, so when we put that into the calculator, we should get the decay constant as 1 .29 times 10 to negative 15 per second or s to negative 1.
01:55
So now we have the decay constant.
01:57
Now the next thing we do is we find how many atoms are present in one milligram of iodine...