MCAT 2002 form BG

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Tweetie_bird

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****ty, just plain ****ty. What did y'all think about it? I can't believe how crappy that test was. All the stuff I studied....I might as well not have studied with the way the test was made. There would be no difference in scores.

Few quick things about specific questions:

1. The question about a gene increasing in frequency, and a chart was given. I believe the question was "when does the Heterozygote frequency increase most...." or something like that. I don't even remember what I picked, but what was the answer?

2. The thing about a parachute dropping something to a bunch of hikers on ground. The plane is going 100 m/s and is 500m above ground. What horizontal distance should they be away from the hikers to make sure that the package falls within their reach? I guessed--500m. What the hell was that?

3. Insulin most likely looks like--oxytocin, epinephrine, cortisol and something else. I picked Epi b/c I assumed it was a peptide hormone and works through second messenger much like Epi. Is that even right?

4. Why does something in water travel faster than in air? I picked the answer about how water molecules are closer together, and air molecules are further apart. Is that right?

5. The whole diarrhoea passage! EEK! Was that a bacteria or was it a virus?? I picked Parasitic Animal (b/c it lived in the villi of the intestines and replicated there..therefore, it was parasitic.) Also, the RNA transcript found in it....did it belong to the bacteria or a virus within it?? I picked the latter b/c when gene sequences were compared across different species of that bacteria, nothing was found in common. Therefore, it would have to be a virus. Plus, they said that cell wall antibiotics didn't work on it...which means resistance could be conferred upon the bacteria by the virus.
I hope I have this right.

Please...help me calm my fears! <img border="0" title="" alt="[Frown]" src="frown.gif" />

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The one with the sheep I said they are able to give birth in the morning while hiding in the bushes. It seemed plausible enough for me, and I narrowed it down to 50/50 anyhow.
 
I agree with LittleMD's reasoning there. I know theoretically if one were to raise the threshold, that would work. But I was debating whether it was possible to do that with a drug, which is what they were asking for. The other choice I was looking at was reducing the Chloride (or was it Potassium?) channels. By keeping the membrane permanently depolarized, you inactivate it. I don't even remember what I put for that one, but again, it was 50/50.
 
what did you guys put for what CrO3 does to the alcohol???
a) oxidize it to an aldehyde
b) oxidize it to a cbx.acid
c) reduce it to an aldehyde
d) reduce it to a cbx. acid

i think i put (b),i am horrible with orgo.
 
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yup, i put that the sheep are able to give birth in the morning while hiding in the bushes.

it seemed more reasonable than the other answers.

also, for my earlier question, doesn't an aldehyde get further oxidized to a cbx. acid?
 
It usually can if it is a strong oxidating agent like potassium dichromate (K2Cr207?) but CrO3 is a weakly oxidating agent that goes only to the level of aldehydes.
 
•••quote:•••Originally posted by LittleMD:
•what did you guys put for what CrO3 does to the alcohol???
a) oxidize it to an aldehyde
b) oxidize it to a cbx.acid
c) reduce it to an aldehyde
d) reduce it to a cbx. acid

i think i put (b),i am horrible with orgo.•••••They specified that it was a primary alcohol that was being reacted with CrO3, so it had to be either a or b. And I put a because as stated above CrO3 is not the strongest of oxiding agents.
 
•••quote:•••Originally posted by calbears84:
•i stared at this one for 5 minutes too :-(
a person eats nothing but protein. what increase in the person's urine? iz either urea or amino acid.•••••This is a very vague question. I think the AAMC should pull it. Urea is always gonna be found in the urine, isn't it? But, amino acids are reabsorbed in the body. However, if you dramatically increase your protein consumption, then the transport mechanism responsible for reabsorption will become overloaded and you'll have amino acids in your urine. Anyone else see that this is a bad question w/ 2 potential answers?
 
•••quote:•••Originally posted by calbears84:
•i stared at this one for 5 minutes too :-(
a person eats nothing but protein. what increase in the person's urine? iz either urea or amino acid.•••••I probably totally missed it, but I put down ketones for my answer. The reason I did this was because I had remembered somewhere that diets, such as the Atkins diet, are high in protein and the danger of such diets is that they can cause the body to go into ketoacidosis. I sometimes tend to read a little too much into questions and it gets me in a lot of trouble.
 
•••quote:•••Originally posted by Medical123:
• •••quote:•••Originally posted by calbears84:
•i stared at this one for 5 minutes too :-(
a person eats nothing but protein. what increase in the person's urine? iz either urea or amino acid.•••••I probably totally missed it, but I put down ketones for my answer. The reason I did this was because I had remembered somewhere that diets, such as the Atkins diet, are high in protein and the danger of such diets is that they can cause the body to go into ketoacidosis. I sometimes tend to read a little too much into questions and it gets me in a lot of trouble.•••••I see your reasoning, but like you said, I think you're reading too much into it. I don't think that most students are expected to know that fact. Ketone bodies are byproducts of fatty acid oxidation, what the whole Atkins diet is centered around. However, I don't think that the original question stated that "if a person eats nothing but protein," but rather if "one were to significantly increase their protein consumption." In other words, they would still be consuming the same amount of carbs etc, which Atkins cuts down on in order to induce ketoacidosis. Messed up question IMHO.
 
I agree, I thought that urea and a.a.'s were both legit answers. I put urea, cuz I figured that the body would need to rid of the nitrogen excess some how, and if it doesn't, then it would be toxic to the body.

Ketoacidosis is a result of too much fatty acid breakdown,... the atkin's diet increases fat consumption (as well as protein consumption) in proportion to carbs so that the body will break down its fat stores. so i think the answer is not likely to be ketone bodies, unless it said that the person was eating less carbs.
 
does anyone remember the one optics question? Something with 2cm,... 20m,... i think.
 
•••quote:•••Originally posted by LittleMD:
•does anyone remember the one optics question? Something with 2cm,... 20m,... i think.•••••Was that the one where the camera was hanging from the balloon? I can't remember the exact question now, but it was something about having to tell them what kind of lens and focal length would be best to photograph some object.

Darn it! I STILL can't believe that I let myself get tricked into reading too much into that urea question!! I've done it at least 3 or 4 times on every darned practice test I took! :p
 
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•••quote:•••Originally posted by LittleMD:
•does anyone remember the one optics question? Something with 2cm,... 20m,... i think.•••••Yeah, it asked about what kinda lens would be needed to create a real image. The focal length was given to be 10 cm. I put converging lens with an object distance of 20cm, b/c converging lenses make real images as long as the object is not within the focal distance (i.e 10cm). They had converging lens and an object distance of 10 cm as an answer choice as well. Diverging lenses make virtual, not real, images, so you could rule out the other two answers. I think my reasoning is right, I dunno. Anyone else think that the more we disect this exam, the worse we're going to feel? <img border="0" title="" alt="[Frown]" src="frown.gif" />
 
•••quote:•••does anyone remember the one optics question? Something with 2cm,... 20m,... i think.••••Q: Lenses, o is &gt;200m, how to make i virtual/real? at 20cm:
a) converging lens, f = 20 cm
b) converging lens, f = 10 cm
c) diverging lens, f = 20 cm
d) diverging lens, f = 10 cm

I forgot whether the question wants virtual or real image. I think I put b) converging lens, f=10cm to make i real & inverted at 20 cm.

Protein consumption: I think the passage stated that "if a person eats nothing but protein," however, in either case, there would be an increase in urea byproducts.

•••quote:•••Primary alcohol + CrO3:
a) oxidize it to an aldehyde
b) oxidize it to a carboxylic acid
c) reduce it to an aldehyde
d) reduce it to a cbx. acid</font>•••The question was: Primary alcohol reacts with aqueous CrO3 to give?

After being oxidized to aldehyde, I think it would then be further oxidized to COOH.

Sheep birth time:
I put an answer that allows them to maximize their reproductive potential, I think it's "give birth in morning while hiding in bushes"

IGFs:
The IGFs passage, I don't remember much about it either. The last question was really tough as I couldn't formulate any basis for my guess.
 
•••quote:•••Originally posted by Fo Shizzel My Nizzel: I put converging lens with an object distance of 20cm, b/c converging lenses make real images as long as the object is not within the focal distance (i.e 10cm). They had converging lens and an object distance of 10 cm as an answer choice as well. Diverging lenses make virtual, not real, images, so you could rule out the other two answers. I think my reasoning is right, I dunno. Anyone else think that the more we disect this exam, the worse we're going to feel? :([/QB]••••I think that I put down the same answer for that one. I was feeling pretty good yesterday when I started looking at this thread, but I am beginning to feel much worse. However, this thread is so addictive that I keep coming back to it. Maybe I need to get one of those T-shirts. :)
 
hey...

why remove the hypo? not cos it's harder tro get to..it's RIGHT by the pit. I put cos it's not developed enough yet..I think that's what I put anyway :-/ not sure...
 
•••quote:•••Originally posted by Medical123:
• •••quote:•••Originally posted by calbears84:
•i stared at this one for 5 minutes too :-(
a person eats nothing but protein. what increase in the person's urine? iz either urea or amino acid.•••••I probably totally missed it, but I put down ketones for my answer. The reason I did this was because I had remembered somewhere that diets, such as the Atkins diet, are high in protein and the danger of such diets is that they can cause the body to go into ketoacidosis. I sometimes tend to read a little too much into questions and it gets me in a lot of trouble.•••••it was Urea..why? They said that the OTHER PARTS of their diet remained *unchanged*. Ergo, ketoacidosis would not occur, but a higher urea concentration would be observed!
 
CrO3 is an oxidizing agent (JONES reagant) it will give the aldehyde then the carboxylic acid. I put carboxylic acid then I switched it. I f'ed up. But if I remember correctly there was something in the passage that made me switch.... anyone remember if there was.
 
Interesting... for that one I saw in the passage that the group of compounds that could be identified by Cr03 were aldehydes and some alcohols. I figured if Cr03 only oxidized to the aldehyde stage, how could aldehydes react with Cr03?? So I put oxidized to carboxylic acid.
 
The answer to the question about increasing protien in ones diet while maintaining everything else is that protiens and amino acids are broken down when they are ingested in access. The carbons are used and NH3 groups are left. This is toxic to the body(basic in pH 7.4 b/c pka is around 9-10) and it's quickly converted into urea and excreted.

So more urea in urine was answer. You don't excrete protiens or amino acids unless they filter thru the glomerulus, which would mean you're having major kidney problems.
 
I agree with you Uscpremed, i think you need CrO3 and PCC (or something like it) to only reduce a primary alcohol to aldehyde.
 
•••quote:•••Originally posted by jofrbr76:
•I agree with you Uscpremed, i think you need CrO3 and PCC (or something like it) to only reduce a primary alcohol to aldehyde.•••••actually, cr03 gives carbox acid, while pcc= aldehyde..cheers
 
I'm positive CrO3 gives the carboxylic acid, I looked in my Orgo notes. Obviously the aldehyde comes first then the acid... but something made me put aldehydes and I can't remember what... there was something in the passage...
 
•••quote:•••Originally posted by Blitzkrieg:
•ya..for the fish, I put that it depends on the density of the fluid AND the volume of water displaced by the fish..I knew it had to include density of fluid, and the other answer that included that also had "volume of water around fish", and that can't be right...ah...

Oh, and the forces acting against the fish when rising: gravity and drag from water, right?

BTW..what is this talk of "experimental passage"? I'm lost.•••••I am assuming that "drag from water" was a wrong choice b/c it said that there are NO frictional forces, right? Please tell me I am right.
 
•••quote:•••Originally posted by Mish550:
•What layer of the skin does leather come from? Is it the dermis or the epidermis?

I picked EPIdermis, b/c it is the tough...outer ..etc etc. Hope it's right.

Also, there was a question that was related to muscle contraction and talked about a problem where muscle contracts all at the same time and askes us what should be done to resolve this problem? Choices were like increase the threshold, inreease Na concentration, etc.....any idea??•••••That was a tricky one. My answer involved the one with decreasing the length of depolarization in the axon. All 3 other choices would set up the gradient in such a way, that it would have MORE Na on the outside than inside, thus inducing even MORE depolarization, which is NOT what we want. Make sense?
 
•••quote:•••Originally posted by Blitzkrieg:
•dude, I'm not sure if it's alkane or alkyl halide..will check tomorrow when I get back to school (will look @ orgo book)

cheers,

blitz•••••I believe it's Alkyl Halide. See, an alkane would not have reacted with either NaOH, or the Base. Nor would it have reacted with AgNO3. Right?? Gosh, i hope I am right.
 
•••quote:•••Originally posted by LittleMD:
•I agree, I thought that urea and a.a.'s were both legit answers. I put urea, cuz I figured that the body would need to rid of the nitrogen excess some how, and if it doesn't, then it would be toxic to the body.

Ketoacidosis is a result of too much fatty acid breakdown,... the atkin's diet increases fat consumption (as well as protein consumption) in proportion to carbs so that the body will break down its fat stores. so i think the answer is not likely to be ketone bodies, unless it said that the person was eating less carbs.•••••Amino acids should not be found in urine of normal people, unless they have nephrotic diabetes or something like that. Basically, your glomerulus would have to be damaged to let A.A. pass through. Urea on the other hand, can diffuse through every part of the nephron in and out...it's very permeable in all situations. Hence, whatever amino acids are de-aminated in the liver (?) are reacted with CO2 in the body to produce Urea which is the easiest way to get rid of NH3 in the body since it's toxic.
 
•••quote:•••Primary alcohol + CrO3:
a) oxidize it to an aldehyde
b) oxidize it to a carboxylic acid
c) reduce it to an aldehyde
d) reduce it to a cbx. acid</font>•••The question was: Primary alcohol reacts with aqueous CrO3 to give?
After being oxidized to aldehyde, I think it would then be further oxidized to COOH.

Anything that is oxidized by Chromium is ALWAYS made into aldehyde. It's just not as strong as KMnO4 or Ozone to make it go to COOH. Plus, the passage stated that fact too.

Sheep birth time:
I put an answer that allows them to maximize their reproductive potential, I think it's "give birth in morning while hiding in bushes"....to stay away from predators. Wrong answer choice according to me.

There was another answer along the lines of ..."to give birth in the right month, and max. their reproductive potential." Don't forget that the passage was about giving Cortisol/ACTH injetions to induce birth. If there are peaks in Cortisol, it would have to be to induce birth at a specific/particular gestation time. Not to hide from predators in the bushes. Is that correct reasoning?

IGFs:
The IGFs passage, I don't remember much about it either. The last question was really tough as I couldn't formulate any basis for my guess.[/QB][/QUOTE]
 
•••quote:•••so what's your answer for the Cr03? Aldehyde or Carboxylic Acid.••••COOH

(i)Oxidation of Primary Alcohols and Aldehydes
Most common oxidizing agents are:KMnO4,CrO3, HNO3, Ag2O (for aldehydes)
(http://www.chemistry.nus.edu.sg/gem1516/chapter07.ppt)

"Oxidation of primary alcohols produces aldehydes .... (Common oxidizing agents include, chromic anhydride, CrO3 , in sulfuric acid; potassium dichromate in sulfuric acid; and potassium permanganate.) .... Aldehyde produced will continue to react producing an acid unless the aldehyde is removed from the reaction mixture."
(http://sunny.crk.umn.edu/courses/ChemHolm/1401/Lab-Procedures-Handout/LabEx5Alcohols-Phenols.doc)
 
•••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Primary alcohol + CrO3:
a) oxidize it to an aldehyde
b) oxidize it to a carboxylic acid
c) reduce it to an aldehyde
d) reduce it to a cbx. acid</font>•••The question was: Primary alcohol reacts with aqueous CrO3 to give?
After being oxidized to aldehyde, I think it would then be further oxidized to COOH.

Anything that is oxidized by Chromium is ALWAYS made into aldehyde. It's just not as strong as KMnO4 or Ozone to make it go to COOH. Plus, the passage stated that fact too.

Sheep birth time:
I put an answer that allows them to maximize their reproductive potential, I think it's "give birth in morning while hiding in bushes"....to stay away from predators. Wrong answer choice according to me.

There was another answer along the lines of ..."to give birth in the right month, and max. their reproductive potential." Don't forget that the passage was about giving Cortisol/ACTH injetions to induce birth. If there are peaks in Cortisol, it would have to be to induce birth at a specific/particular gestation time. Not to hide from predators in the bushes. Is that correct reasoning?

IGFs:
The IGFs passage, I don't remember much about it either. The last question was really tough as I couldn't formulate any basis for my guess.•••••[/QB][/QUOTE]

WRONG tweetie..it goes to carb acid..I checked my orgo book and w/my teacher.

Alkyl halide is the answer..

the ansswer is to hide in the bushes in the morn...

Cr03 is strong enough..in fact, it is very strong. Where do ppl get otherwise? You're thinking of PCC which only goes to aldehyde
 
•••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Originally posted by Blitzkrieg:
•ya..for the fish, I put that it depends on the density of the fluid AND the volume of water displaced by the fish..I knew it had to include density of fluid, and the other answer that included that also had "volume of water around fish", and that can't be right...ah...

Oh, and the forces acting against the fish when rising: gravity and drag from water, right?

BTW..what is this talk of "experimental passage"? I'm lost.•••••I am assuming that "drag from water" was a wrong choice b/c it said that there are NO frictional forces, right? Please tell me I am right.•••••um....it never said no frictional forces. It was basically a stand alone question, apart from the passage. It's drag and gravity.
 
•••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Originally posted by Mish550:
•What layer of the skin does leather come from? Is it the dermis or the epidermis?

I picked EPIdermis, b/c it is the tough...outer ..etc etc. Hope it's right.

Also, there was a question that was related to muscle contraction and talked about a problem where muscle contracts all at the same time and askes us what should be done to resolve this problem? Choices were like increase the threshold, inreease Na concentration, etc.....any idea??•••••That was a tricky one. My answer involved the one with decreasing the length of depolarization in the axon. All 3 other choices would set up the gradient in such a way, that it would have MORE Na on the outside than inside, thus inducing even MORE depolarization, which is NOT what we want. Make sense?•••••increase threshold, making it harder to fire, and thus reducing frequency of firing
 
•••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Primary alcohol + CrO3:
a) oxidize it to an aldehyde
b) oxidize it to a carboxylic acid
c) reduce it to an aldehyde
d) reduce it to a cbx. acid</font>•••The question was: Primary alcohol reacts with aqueous CrO3 to give?
After being oxidized to aldehyde, I think it would then be further oxidized to COOH.

Anything that is oxidized by Chromium is ALWAYS made into aldehyde. It's just not as strong as KMnO4 or Ozone to make it go to COOH. Plus, the passage stated that fact too.

Sheep birth time:
I put an answer that allows them to maximize their reproductive potential, I think it's "give birth in morning while hiding in bushes"....to stay away from predators. Wrong answer choice according to me.

There was another answer along the lines of ..."to give birth in the right month, and max. their reproductive potential." Don't forget that the passage was about giving Cortisol/ACTH injetions to induce birth. If there are peaks in Cortisol, it would have to be to induce birth at a specific/particular gestation time. Not to hide from predators in the bushes. Is that correct reasoning?

IGFs:
The IGFs passage, I don't remember much about it either. The last question was really tough as I couldn't formulate any basis for my guess.•••••[/QB][/QUOTE]

the increased ACTH injection question was related to birthing time...experimental vs control. Experimental group (ACTH recieved) have increased cortisol, thus sooner births than control.
 
Does anyone remember the question about synthesizing antibodies? Where is that done?
 
•••quote:•••Originally posted by Roger Rabbit:
•Tweetie so what's your answer for the Cr03? Aldehyde or Carboxylic Acid.•••••Aldehyde.
 
•••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Originally posted by Roger Rabbit:
•Tweetie so what's your answer for the Cr03? Aldehyde or Carboxylic Acid.•••••Aldehyde.•••••I put down a COOH, b/c Cr03 is Jone's reagent and is a strong oxidizing agent. I checked in my orgo book and the kaplan books, and they both said a primary alcohol with CrO3 goes to a carboxy acid.
 
•••quote:•••Does anyone remember the question about synthesizing antibodies? Where is that done?••••This's another one that's harder than average. I was looking for free ribosome in cytoplasm but that wasn't one of the choices. Choices included RER, SER, nucleus... Since antibodies are to be released out of the cells, they need to go thru the Golgi. Synthesizing in RER would enable it to go thru the Golgi to extracellular space.
 
•••quote:•••Originally posted by Mish550:
• •••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Originally posted by Roger Rabbit:
•Tweetie so what's your answer for the Cr03? Aldehyde or Carboxylic Acid.•••••Aldehyde.•••••I put down a COOH, b/c Cr03 is Jone's reagent and is a strong oxidizing agent. I checked in my orgo book and the kaplan books, and they both said a primary alcohol with CrO3 goes to a carboxy acid.•••••Yeap, you guys are right. Too bad i missed such an easy question...but ...did the passage not say anything about it going just to aldehyde? I guess I am beating a dead horse. :confused:
 
Hi, tweetie.

The previous page had a diagram that showed what reagents reacted with what molecules. It said that CrO4 could oxidize aldehydes and some alcohols, so one has to assume that CrO4 takes a 1o alcohol all the way to COOH. This is because CrO4 oxidizes aldehydes as well as alcohols, and once the alcohol becomes an aldehyde, it will then be futher oxidized to the acid.

HTH
 
Hi, tweetie.

The previous page had a diagram that showed what reagents reacted with what molecules. It said that CrO4 could oxidize aldehydes and some alcohols, so one has to assume that CrO4 takes a 1o alcohol all the way to COOH. This is because CrO4 oxidizes aldehydes as well as alcohols, and once the alcohol becomes an aldehyde, it will then be futher oxidized to the acid.

HTH
 
•••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Originally posted by Roger Rabbit:
•Tweetie so what's your answer for the Cr03? Aldehyde or Carboxylic Acid.•••••Aldehyde.•••••tweetie,

I repeat: you're wrong! Check your orgo book concerning primary alcohol oxidation with CrO3.
 
•••quote:•••Originally posted by Charlie:
• •••quote:•••Does anyone remember the question about synthesizing antibodies? Where is that done?••••This's another one that's harder than average. I was looking for free ribosome in cytoplasm but that wasn't one of the choices. Choices included RER, SER, nucleus... Since antibodies are to be released out of the cells, they need to go thru the Golgi. Synthesizing in RER would enable it to go thru the Golgi to extracellular space.•••••I put RER..antibodies have a protein arm that is unique to that antibody, correct?
 
•••quote:•••Originally posted by Blitzkrieg:
• •••quote:•••Originally posted by Tweetie_bird:
• •••quote:•••Originally posted by Roger Rabbit:
•Tweetie so what's your answer for the Cr03? Aldehyde or Carboxylic Acid.•••••Aldehyde.•••••tweetie,

I repeat: you're wrong! Check your orgo book concerning primary alcohol oxidation with CrO3.•••••dude, just chill...it's not like this is a court of law. Did you not see my previous post where I mentioned that I was wrong????? Let's try to be a bit civil here, please. Thanks. :wink:

Tweetie
 
hehe..tweetie...

sorry, didn't see your post before. I'm being civil! You misread my tone..uh oh..another reference to VR! :p
 
Dear all,

Here's another question to ponder about. Isn't it great that we all have form BG? :)

Passage: Radical reactions
(R1) Br* + O3 --&gt;?BrO* + O2
(R2)?BrO* + ... --&gt;?Br* + ....

Q: Which of the following, if occurs readily, will contradict the claim that Br* destroys O3:
a) BrO* + O2 --&gt;?Br* + O3
b) BrO* + ClO* --&gt;?BrCl + O2
c)d) ...

A: At first I thought it's a) because it's the reverse of reaction R1, but then I thought it still doesn't terminate the radical reaction chain. I then chose b) BrO* + ClO* --&gt; BrCl + O2 'cause although I think BrCl is unlikely, the reaction does put an end to Br* production.
 
•••quote:•••Originally posted by Charlie:
•Dear all,

Here's another question to ponder about. Isn't it great that we all have form BG? :)

Passage: Radical reactions
(R1) Br* + O3 --&gt;?BrO* + O2
(R2)?BrO* + ... --&gt;?Br* + ....

Q: Which of the following, if occurs readily, will contradict the claim that Br* destroys O3:
a) BrO* + O2 --&gt;?Br* + O3
b) BrO* + ClO* --&gt;?BrCl + O2
c)d) ...

A: At first I thought it's a) because it's the reverse of reaction R1, but then I thought it still doesn't terminate the radical reaction chain. I then chose b) BrO* + ClO* --&gt; BrCl + O2 'cause although I think BrCl is unlikely, the reaction does put an end to Br* production.•••••I was not sure about that question either. I think I put the same answer you did. It definitely looks familiar!
 
I initially had b but with 5 seconds left, switched it to a. I guess my reasoning was O3 is a product in reaction a, so wouldn't that contradict the claim that it helps breakdown ozone? Plus, the BrCl just looked odd to me. I dunno. Oh well, the more I think about this exam, the worse I'm feeling, so I think I'll stay away from this thread. <img border="0" title="" alt="[Frown]" src="frown.gif" />
 
•••quote:•••Originally posted by Charlie:
•Dear all,

Here's another question to ponder about. Isn't it great that we all have form BG? :)

Passage: Radical reactions
(R1) Br* + O3 --&gt;?BrO* + O2
(R2)?BrO* + ... --&gt;?Br* + ....

Q: Which of the following, if occurs readily, will contradict the claim that Br* destroys O3:
a) BrO* + O2 --&gt;?Br* + O3
b) BrO* + ClO* --&gt;?BrCl + O2
c)d) ...

A: At first I thought it's a) because it's the reverse of reaction R1, but then I thought it still doesn't terminate the radical reaction chain. I then chose b) BrO* + ClO* --&gt; BrCl + O2 'cause although I think BrCl is unlikely, the reaction does put an end to Br* production.•••••a..why? because if reaction C occurs, then O3 is still broken down, forming O2 and BrCl. In reaction a, the reaction was started by Br, breaking O3, but ends with O3 and Br. Therefore, there is an equliibrium, and no true "destruction" of O3. Does that sound right?
 
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