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 (b) What is the mass of each isotope?

Video transcript

everyone in this example, we need to calculate the mass of each isotope of chlorine. Given the mass spectrum of chlorine gas were told that to note that there are two isotopes of chlorine and the mass of a cl two molecule is the sum of the masses of the two atoms in the molecule. So based on this mass spectrum, we can see that we go from an atomic mass of 69.938 for a cl two molecule and then we go to up to two units for a mass of 71.935 for the cl two molecule and then buy another two units, we get to a mass of 73.932 am us. And so based on that increase of two units, when we get to the different atomic masses of the molecules, we would say that our two isotopes are going to be chlorine which is our atomic mass from the periodic table of chlorine. And then our second isotope will be two units above that, which is chlorine 37 as our second isotope. And so our formation of chlorine gas arises from taking two, multiplied by our atomic mass of our chlorine adam here. And this gives us our cl two molecule with the atomic mass, which we can round to about 70. And we'll make that a capital M for atomic mass For the formation of our next chlorine gas molecule, we would have the isotope 35 chlorine and 37 chlorine masses added together to give us a atomic mass equal to about 72. And then for the formation of our chlorine gas here. I'm sorry, I should have wrote the Arrow for Cl two there. So let me just actually make more room. So for the formation of our chlorine gas based on the third bro of our spectrum, we would say that that is two times our isotope of chlorine 37, which forms our cl two molecule with the atomic mass of about 74. Based on the chart given. And so in our chart, we can list this first atomic mass as our peak number one, the second atomic mass as peak too, and a third atomic mass as peak three. And so to find our mass of our isotope chlorine 35 chlorine 37. We can take our peak one and divide that by our peak number three. Or correction, we can rather take our peak one and divide that in two. To get our mass of our isotope chlorine 35 we can take our peak three And divide that by two. To get our mass of our isotope chlorine 37. And so to make more room here, What we should have for our first peak is in the chart that has given us 69.938. We're going to divide that by two. Since we recognize that it was multiplied or our isotope 30 chlorine 35 was multiplied by two to form our chlorine molecule chlorine gas molecule and the writing by two is going to give us a mass equal to 34.969 AM use for our chlorine 35. So this would be our first answer here For our chlorine isotope mass following the same steps for our third peak, which in the chart is given us 73.932. We're going to also divide that by two because we saw that to form our chlorine gas molecule, we took two and we multiplied it by our chlorine 37 here, Which was our second isotope. And this gives us a value equal to 73.932 AM use. And this would be our second and final answer as the atomic mass for our second isotope chlorine 37. So everything boxed in represents our final answers for this question. If you have any other questions, please leave them down below. And I will see everyone in the next practice video