# chemistry

posted by .

1. The mass spectrum can be observed for all forms: pos. ion, neg.ion, molecules, and atoms, can't it?

2. Is there a formular to calculate how many spectrum of the substances we need to observe? Please give me some examples, and calculation.

3. I knew the examples of H2S+, and how to draw the table to find the peak, but I don't know the formula to calculate how many peak without using the table, so I need other examples, and how to calculate peaks.

Thanks a lot

• chemistry -

1. A mass spectromter analyzes ions, or ions formed when a neutral atom or molecule is ionized and broken up before entering the mass analyzer. Since you are analyzing fragments of an original molecuile, it is often difficult to say what the original molecule was. It might have been a different molecule that produces the same ionic fragments.

2. The short answer is no, except that the OPTICAL spectra of one-electron atoms (hydrogen) and ions can be easily calculated. Are you talking about mass spectra or optical spectra?

I am not clear why you ask how many spectra you NEED TO observe. In order to do what? Is this a lab assignment?

3. I have no idea what kind of spectra you are talking about here

• chemistry -

Thank you drwls

i am reviewing my chemistry and doing the problems from my textbook. Because my teacher did not have the lecture about this part, so I am reading my text book and trying to solve problems. My textbook only have two problems of this theory:

1/ find how many peaks you would observe in the mass spectrum of the positive ion of CF4^+.( C has 2 stable isotopes, F has 1 isotope)
and
2/ Hydrogen has two isotope H1 and H2, and Sulfur has four isotopes S(32), S(33) S (34) and S (35). How many peaks you observed in the mass spectrum of positive ion H2S+

I solved these problems and and checked my answer with the answer key, but I still don't understand a lot. I would like you to explain for me what the optical spectra and mass spectra are,and the difference between them as well as some other examples, please.

• chemistry -

Optical spectra are the wavelengths at which an element or compound emit and absorb light or infrared radiation. That subject used to be a specialty of mine.

Your questions are apparently concerned with mass spectra, not optical spectra. A mass spectrum shows the different charge-to-mass ratios of ions that pass through a device that separate them, based upon the value of that ratio.

Ions for which different elements have different isotopes will exhibit more than one "mass" peak for each ion. The spectrum looks like a series of "peaks" or "spikes" of different intensity. The strongest ones will correspond to the most abundant mass values.

1. CF4+ will have two possible masses (in amu units) of 12 + 4*19 = 88 or 13 + 4*19 = 89. The 88 peak will be about 99 times higher because C12 is 99 times more abumndant than C13.

2. H2S can have three possible mass values for the H2 part (1+1 = 2, 1+2 = 3, or 2+2 = 4) and 4 possible values for the S atom (32, 33, 34 or 35). The number of possible masses of the combined H2S+ ion are:
2+32 = 34
2+33 OR 3+32= 35
2+34 OR 3+33 OR 4+34 = 36
2+35 OR 3+34 OR 4+33 = 37
3+35 OR 4+34 = 38
4+35 = 39
That is a total of 6 possible lines.

Just construct a table with all the possible mass combinations, and count them, as I did above. There is probably a formula one could write, but it will differ depending upon what the different possible isotope mass values are, and how many atoms of each type there are in the molecular ion.

• chemistry -

Thank you so much drwls

## Similar Questions

1. ### Chemistry

What is the wavelength of the transition from n=4 to n=3 for Li2+?
2. ### Chemistry

What is the wavelength of the transition from n=4 to n=3 for Li2+?
3. ### DrBob222-Questions

Can you please check these for me. Thank you very much in return:-) For Al2(SO4)3 you gave me Aluminum ion and Sulfate ion. These are the rest: CaCl2 = Calcium ion and Chlorite ion Na2O = Sodium ion and Oxygen ion AgCl = silver ion …
4. ### Physics

What type of spectrum is produced by a hydrogen gas when a high potential difference is applied to it?
5. ### algebra

What does Descartes Rule of Signs tell you about the real roots of the polynomial -2x^3+3x^3-5x-2=0 possible answers one positive root either 2 or 0 neg 2 or 0 pos and 2 or 0 neg one pos and one neg either 2 or 0 pos and one neg
6. ### chemistry

A gas in a discharge tube consists entirely of ions of the same element, of the same charge. Each ion has only one remaining electron. The voltage between the electrodes of the gas discharge tube is increased from zero. Electrons are …
7. ### Chemistry

A gas in a discharge tube consists entirely of ions of the same element, of the same charge. Each ion has only one remaining electron. The voltage between the electrodes of the gas discharge tube is increased from zero. Electrons are …
8. ### Chemistry.........

Elemental chlorine exists as a diatomic molecule Cl2. Chlorine atoms exist in two different isotopes 35Cl and 37Cl. In the mass spectrum of chlorine molecules, how may peaks due to chlorine atoms would be observed?
9. ### chemistry

Explain how understanding of the atomic emmission spectrum led to developement of the atomic theory. The emmissions spectrum for each element is unique. You can identify an eleement by its spectrum. The atomic theory states that all …
10. ### chemistry

Back to the atomic emmission spectrum and the atomic theory. in the 1900s, scientists observed that when a gaseous element, such as hydrogen was subjected to an electric discarge that the atoms emitted electromagnetic radiation. The …

More Similar Questions