The accompanying graph illustrates the decay of ⁸⁸₄₂Mo, which decays via positron emission. (a) What is the halflife of the decay? [Section 21.4]

Video transcript

Welcome back everyone. We're told that the decay of selenium 72 by electron capture is illustrated in the following plot. And based on this plot, estimate the half life of the decay. So based on our plot below, we can see that we begin with a mass of our selenium 72 of about one g here. Because on our white access it's measured in units of g. So we can say we begin at one graham of Selenium 72. And we recognize from the plot that with the decay of electron capture or by electron capture of our selenium 72 We're going to lose 50% of this initial mass of our selenium 72. And so half of our initial mass of one g is going to be about we would say .5 here. So we'll say after Electron capture we have about .5g of our selenium 72 left or that remains. And so going to this point point five here 50.5 g. We're gonna carry this across to our line and we're going to see that this land us just a bit past eight days. So we'll say that this is about and let's actually draw the line in. So 0.5 g going to our graph will say that this hits at just about 8.3 and our X axis is measured in days. So we would say that Our half life of our selenium 72 Is about 8. days. And this would be our final answer. 8.5 days that it takes for our electron capture to leave us with .5g of our selenium 72. I hope everything I reviewed was clear. If you have any questions, leave them down below and I'll see everyone in the next practice video.