There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of Br₂ molecules, and the mass of a Br₂ molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of Br₂ consists of three peaks: Mass (u) Relative Size 157.836 0.2569 159.834 0.4999 161.832 0.2431 (e) Calculate the abundances of the two isotopes. Calculate the abundance of the heavier isotope.

Video transcript

everyone here, we have a question to ask, nitrogen has two stable isotopes, nitrogen 14 and nitrogen 15. If a sample of nitrogen gas into is analyzed using mass spectrometry, the following peaks are obtained 28 at 100% MZ 29 at 290.731% and MZ 30 as 0.1%. Using this data calculate the abundance of each isotope. So our abundance equals the high of our peak due to isotope m divided by the height of our peak due to isotope in plus the height of our peak due to isotope M plus one Times 100%. So first we're going to solve for the abundance of in 14. So the peak at 28 is due to two in 14 atoms because we have the 14 plus 14 equals 28 the peak at 29 is due to one in 14 and one in 15, nitrogen is a di atomic molecules. So we have into so there's an equal probability that either of the two atoms can be an N 15 or an N 14. So we're going to divide the height of the N plus one peak by two. And now we can solve for the abundance um in 14. So that's going to equal over Plus 0. 55 Times 100%. And that equals 9. point 636. So that is our abundance of in 14 and now we can find our abundance of in 15 by just subtracting minus 99. Sorry, that's 99.636. So we can take 100 -99. And that equals 0.364%. So that is our abundance of in 14 and our abundance of in 15. Thank you for watching. Bye.