00:01
To write a balanced nuclear equation for the beta emission of phosphorus 32, we'll start with phosphorus 32, go to the periodic table and look at the atomic number of phosphorus, which is 15.
00:18
Then when it undergoes beta decay, it'll release an electron with no mass and a minus one charge.
00:25
So the daughter nucleide needs to have a mass number of 32, so 32 plus 0 gives us 32.
00:32
And an atomic number of 16, so 16 minus 1, gives us 15.
00:39
And the element that has an atomic number of 16 is sulfur, so the daughter nucleide will be sulfur 32.
00:50
Then it wants to know, given the half -life, how long it would take, or how much mass would remain after 28 .6 days.
01:01
Well, all radioactive decay follows first -order kinetic, that means that we can use the first order half -life equation in order to calculate the decay constant.
01:11
The first -order half -life equation is the natural log of 2 divided by the half -life equals k.
01:22
The half -life they've given us is 14 .3 days...