00:01
Question 101 describes the half -life of bromine 82 being 1 .471 days.
00:08
This isotope decays by the emission of a beta particle.
00:14
In addition, when hbr containing bromine 82 decays, it produces hydrogen gas.
00:27
So the nuclear equation is going to be br -82, emitting a beta particle, producing something that has a mass number of 82, and an at a total.
00:38
Atomic number of 36.
00:41
36 minus 1 gives us 35.
00:44
Element 36 is krypton.
00:48
So, hbr 82, undergoing decay, is going to generate the hydrogen gas, and what will be left over will not be bromine, but rather krypton 82, as we described up here.
01:04
The stoichiometry is going to be two hbr 82's, going to one hydrogen and two krypton's.
01:15
To determine the amount that remains after 12 hours, we need to solve for the decay constant.
01:23
The decay constant will be the half -life provided at 1 .471 days divided into the natural log of 2 or 0 .471 days.
01:37
So using the first -order integrated rate law, the natural log of the amount of the radioactive species remaining at time t, divided by the amount that we have initially .0 .0 .150 moles.
01:54
If we have 0 .1 .50 moles of hbr, we have that many moles of the br82...