Hydrogen has two stable isotopes, 1^1 H and 1^2 H, and sulfur has four stable isotopes, 16^32

step 1 Okay, we're told that hydrogen has two stable isotopes. Those two isotopes are proteum and deute

Hydrogen has two stable isotopes, 1^1 H and 1^2 H, and...

Hydrogen has two stable isotopes, ${ }_{1}^{1} \mathrm{H}$ and ${ }_{1}^{2} \mathrm{H},$ and sulfur has four stable isotopes, ${ }_{16}^{32} \mathrm{~S},{ }_{16}^{33} \mathrm{~S},{ }_{16}^{34} \mathrm{~S},$ and ${ }_{16}^{36} \mathrm{~S}$. How many peaks would you observe in the mass spectrum of the positive ion of hydrogen sulfide, $\mathrm{H}_{2} \mathrm{~S}^{+} ?$ Assume no decomposition of the ion into smaller fragments.

Key Concepts

Isotopes

Isotopes are forms of the same element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. This concept is critical because the presence of multiple stable isotopes for hydrogen and sulfur creates different mass combinations when atoms form molecules.

Mass Spectrometry

Mass spectrometry is an analytical technique used to determine the masses of particles, such as ions, by measuring their mass-to-charge ratios. In the context of molecular ions, different isotopic compositions result in multiple peaks corresponding to different molecular masses, which can be used to deduce structural and quantitative information about the sample.

Positive Ionization

Positive ionization refers to the process of forming positively charged ions, often by adding or removing electrons. This process is essential in mass spectrometry, as it allows the sample molecules to be detected based on their unique mass-to-charge ratios. The formation of a positive ion like H2S+ directly relates to the way isotopic combinations are detected in the mass spectrum.

Combinatorial Analysis of Isotopic Species

Combinatorial analysis involves determining the number of possible combinations of isotopes in a molecule. When a molecule consists of atoms with multiple isotopes, the different possible combinations of these isotopes lead to distinct molecular masses. This analysis is fundamental in predicting the number of peaks in a mass spectrum when considering all the isotopic variations.

Transcript

00:01 Okay, we're told that hydrogen has two stable isotopes.

00:18 Those two isotopes are proteum and deuterium.

00:35 Okay, sulfur has four stable isotopes.

00:49 And those are always 16.

01:00 We've got 32, 33, 34, and 36.

01:10 Okay, how many peaks would you observe in the hydrogen sulfide, sulfide, positive ion, h2s plus? i'd assume no decomposition, but i'm not going to put that in here.

01:43 Okay, let's see if we can figure out how to do this.

01:47 So the four sable isotopes, so hydrogen can pair as, so i could have my hydrogen for my h2 could be h2, both ones, i could have h2 both twos, or i could have h2 both twos, or i could have h2, i could have h -1 -1 and h -21.

02:29 Those are my three possible pairings for hydrogen.

02:40 So each one of those pairings, so let's see what those pairings would look like.

02:54 So if i have h -1 -1, h -1, and then do my 32 -16, this would have a mass number of 32, 33, 33, 32, 33, 34.

03:25 This is 34 amus.

03:33 Then h112, 16, 34.

03:39 Is it 33? would be 35.

03:51 H211.

03:53 34, 16 would be 36.

03:59 And h21136 would be 38.

04:06 So those are my four possible...