Forensics C

[wec01]

1. Who developed DNA sequencing?
2. what is the outside layer of the skin called?
3. What is the refractive index of water?

1. Frederick Sanger
2. Epidermis
3. 1.33

[Crimesolver]

yup your turn

[wec01]

You are given a mass spectra of a gas that has a molecular ion peak at m/z = 44. The largest peak is at m/z = 29 and there is a small peak at m/z = 15. What was the gas?

[CPScienceDude]

You are given a mass spectra of a gas that has a molecular ion peak at m/z = 44. The largest peak is at m/z = 29 and there is a small peak at m/z = 15. What was the gas?

Argon? I have no idea how to actually do these so that's probably wrong.

[pikachu4919]

You are given a mass spectra of a gas that has a molecular ion peak at m/z = 44. The largest peak is at m/z = 29 and there is a small peak at m/z = 15. What was the gas?

Argon? I have no idea how to actually do these so that's probably wrong.

Think about how a mass spectrometer works - when the sample is fed into the machine, it is first ionized, where it is broken apart into smaller pieces, and then it passes through a magnetic field that separates the pieces by size via deflection during this process, and the generated spectra is a representative of all the possible pieces of different masses that resulted from the ionization and deflection.

A noble gas like argon is more likely to be found as just itself and not in combinations with other elements unless some crazy combination with possibly other halogens takes place (such as XeF₈, but xenon is pretty far down the periodic table so it has other f and d orbitals that can facilitate all those fluorides, which argon lacks due to not having those kinds of structural components), and also due to its structure of having full electron shells, even though it isn't impossible, it would take an incredible amount of energy to break the atoms into their smaller parts, much more than a mass spectrometer can possibly exert during ionization. So, if you collected a mass spectra of argon, it's more likely that it would show one peak at its molecular mass, which is 40 (proven by NIST).

That being said, since it's a gas and that narrows things down by a lot, the most likely options you could think of off the top of your head would probably be narrowed down to nitrous oxide (N₂O) and carbon dioxide (CO₂) since they have molecular masses of 44, but it's not likely to be those since they are very tightly bonded to each other, using double bonds (and in the case of N₂O, both double and triple bonds), in which the energy required to break those bonds is once again significant, in which it would make more sense for, the base peak would be much closer to the M+ peak even if peaks also appear at smaller m/z values. What's funny is that acetaldehyde seems to exactly match the description despite not naturally existing as a gas (see here). But ethylene oxide exists as a gas and has the exact same formula as acetaldehyde, and it is incredibly likely to break apart in an ionizer since it's a cyclic ether, which aren't very stable molecules since carbon isn't meant to be in a triangle. So my final answer is ethylene oxide (can be proven here), but someone else (maybe CPScienceDude, if he wants to?) can post the next question instead of me since asking/writing your own questions is a very important way to learn for you all competitors, and I will be writing plenty of questions of my own anyways due to upcoming event supervisor duties.

[wec01]

You are given a mass spectra of a gas that has a molecular ion peak at m/z = 44. The largest peak is at m/z = 29 and there is a small peak at m/z = 15. What was the gas?

Argon? I have no idea how to actually do these so that's probably wrong.

Think about how a mass spectrometer works - when the sample is fed into the machine, it is first ionized, where it is broken apart into smaller pieces, and then it passes through a magnetic field that separates the pieces by size via deflection during this process, and the generated spectra is a representative of all the possible pieces of different masses that resulted from the ionization and deflection.

A noble gas like argon is more likely to be found as just itself and not in combinations with other elements unless some crazy combination with possibly other halogens takes place (such as XeF₈, but xenon is pretty far down the periodic table so it has other f and d orbitals that can facilitate all those fluorides, which argon lacks due to not having those kinds of structural components), and also due to its structure of having full electron shells, even though it isn't impossible, it would take an incredible amount of energy to break the atoms into their smaller parts, much more than a mass spectrometer can possibly exert during ionization. So, if you collected a mass spectra of argon, it's more likely that it would show one peak at its molecular mass, which is 40 (proven by NIST).

That being said, since it's a gas and that narrows things down by a lot, the most likely options you could think of off the top of your head would probably be narrowed down to nitrous oxide (N₂O) and carbon dioxide (CO₂) since they have molecular masses of 44, but it's not likely to be those since they are very tightly bonded to each other, using double bonds (and in the case of N₂O, both double and triple bonds), in which the energy required to break those bonds is once again significant, in which it would make more sense for, the base peak would be much closer to the M+ peak even if peaks also appear at smaller m/z values. What's funny is that acetaldehyde seems to exactly match the description despite not naturally existing as a gas (see here). But ethylene oxide exists as a gas and has the exact same formula as acetaldehyde, and it is incredibly likely to break apart in an ionizer since it's a cyclic ether, which aren't very stable molecules since carbon isn't meant to be in a triangle. So my final answer is ethylene oxide (can be proven here), but someone else (maybe CPScienceDude, if he wants to?) can post the next question instead of me since asking/writing your own questions is a very important way to learn for you all competitors, and I will be writing plenty of questions of my own anyways due to upcoming event supervisor duties.

To be honest, I was going for propane, but the question was vague (and saying that it was a gas was a bit misleading as propane is typically compressed into a liquid) so ethylene oxide is a good answer as well. As pikachu4919 said, whoever wants to ask next, go ahead.

[pikachu4919]

Argon? I have no idea how to actually do these so that's probably wrong.

Think about how a mass spectrometer works - when the sample is fed into the machine, it is first ionized, where it is broken apart into smaller pieces, and then it passes through a magnetic field that separates the pieces by size via deflection during this process, and the generated spectra is a representative of all the possible pieces of different masses that resulted from the ionization and deflection.

A noble gas like argon is more likely to be found as just itself and not in combinations with other elements unless some crazy combination with possibly other halogens takes place (such as XeF₈, but xenon is pretty far down the periodic table so it has other f and d orbitals that can facilitate all those fluorides, which argon lacks due to not having those kinds of structural components), and also due to its structure of having full electron shells, even though it isn't impossible, it would take an incredible amount of energy to break the atoms into their smaller parts, much more than a mass spectrometer can possibly exert during ionization. So, if you collected a mass spectra of argon, it's more likely that it would show one peak at its molecular mass, which is 40 (proven by NIST).

That being said, since it's a gas and that narrows things down by a lot, the most likely options you could think of off the top of your head would probably be narrowed down to nitrous oxide (N₂O) and carbon dioxide (CO₂) since they have molecular masses of 44, but it's not likely to be those since they are very tightly bonded to each other, using double bonds (and in the case of N₂O, both double and triple bonds), in which the energy required to break those bonds is once again significant, in which it would make more sense for, the base peak would be much closer to the M+ peak even if peaks also appear at smaller m/z values. What's funny is that acetaldehyde seems to exactly match the description despite not naturally existing as a gas (see here). But ethylene oxide exists as a gas and has the exact same formula as acetaldehyde, and it is incredibly likely to break apart in an ionizer since it's a cyclic ether, which aren't very stable molecules since carbon isn't meant to be in a triangle. So my final answer is ethylene oxide (can be proven here), but someone else (maybe CPScienceDude, if he wants to?) can post the next question instead of me since asking/writing your own questions is a very important way to learn for you all competitors, and I will be writing plenty of questions of my own anyways due to upcoming event supervisor duties.

To be honest, I was going for propane, but the question was vague (and saying that it was a gas was a bit misleading as propane is typically compressed into a liquid) so ethylene oxide is a good answer as well. As pikachu4919 said, whoever wants to ask next, go ahead.

Yeah, the rules being limited to mass spec is unfortunate because allowing usage of another kind of spectrometry, like IR or NMR, would definitely enable clearing up that difference. I guess a lot of spectrometry stuff is hard to understand, though, which is why it isn’t there (even though MatSci did include some of that so...welp, I guess) ^that wasn’t a question, someone else post a question.

[viditpok]

1. What law is used to determine the ratio of the angle of incident and the angle of refraction, based on either velocity or refractive index? (The name of the law should include the name of the person it was named after, not just "the law of refraction")

2. What are the five methods used to identify powders?

3. What are the five liquids used to identify powders?

4. What are three different forms of fingerprints?


*These questions are based on the Science Olympiad version of forensics, but in reality, could have different answers*

[jimmy-bond]

1. What law is used to determine the ratio of the angle of incident and the angle of refraction, based on either velocity or refractive index? (The name of the law should include the name of the person it was named after, not just "the law of refraction")

2. What are the five methods used to identify powders?

3. What are the five liquids used to identify powders?

4. What are three different forms of fingerprints?


*These questions are based on the Science Olympiad version of forensics, but in reality, could have different answers*

I crammed out my first study session for this event just today, so I got this 1. Snell's law
2. Not sure what you mean, so I'll go with flame test, solubility, pH, reactivity (to NaOH, HCl, Benedict's, and KI), and good ol' sight
3. NaOH, HCl, Benedict's, KI, water (for solubility and pH)
4. Latent, patent, and plastic

[viditpok]

1. What law is used to determine the ratio of the angle of incident and the angle of refraction, based on either velocity or refractive index? (The name of the law should include the name of the person it was named after, not just "the law of refraction")

2. What are the five methods used to identify powders?

3. What are the five liquids used to identify powders?

4. What are three different forms of fingerprints?


*These questions are based on the Science Olympiad version of forensics, but in reality, could have different answers*

I crammed out my first study session for this event just today, so I got this 1. Snell's law
2. Not sure what you mean, so I'll go with flame test, solubility, pH, reactivity (to NaOH, HCl, Benedict's, and KI), and good ol' sight
3. NaOH, HCl, Benedict's, KI, water (for solubility and pH)
4. Latent, patent, and plastic

Yes, that is pretty much correct! Although all of your answers are correct, I was just looking for this in question 2, instead of sight: Conductivity

Someone please ask the next question