00:01
There are several radioactive isotopes of krypton, including krypton -76.
00:06
It requires 23 .5 hours for 66 .7 % of an initial sample of krypton -76 to decay.
00:18
We have to find the half -life.
00:22
So we're going to use a modified form of the half -life equation equation where the percentage is actually going to be the percent or a fraction.
00:35
So what we're going to do is we're going to change the percentage to a decimal and it's going to be 0 .667 and this is going to be equal to e to the negative lambda t.
00:49
Now what we actually have to do is figure out lambda because that is where our half -life is.
00:56
So our t is going to be 23 .5 hours.
01:02
So if we take the natural logarithm of 0 .667 and that will equal negative lambda times 23 .5 or lambda is equal to the natural logarithm of 0 .667 divided by negative 23 .5.
01:34
So the natural logarithm of 0 .667 and then we're going to divide that by negative 23 .5.
01:44
Our lambda is equal to 0 .01723 and some some change...