1.

For all of them, I am going to describe the carbon and ignore the presence of the hydrogens, which fill the rest of the four possible bonding sites on each carbon atom.

-straight chain of five carbon atoms

-a chain of four carbon atoms with the fifth one coming off of the second carbon in the chain

-a plus shape, with a central carbon, and carbons bonded to each of the 4 bonding sites on it

All other possibilities which I could come up with were able to be created by the inherant flexibility of a single bond

I found 6 different isomers for C5H12. One is a straight line; one is like steps-carbon is connected upwards to another carbon, over to another, up to another, then over again; the next one looks like a chair with a carbon connected upwards to another, then over, and down and up; one looks like an x; another looks like a t; and the last one is a bigger step than the other one that looks like a step-a carbon connected upwards to another carbon then over to another, and over again, and finally upwards to another carbon.

3… the first ( pentane) is a straight chain of 5 carbons, the two end carbons have three bonds with hydrogen and the middle three have two bonds with hydrogen each. The second (2, methyl butane) is a chain of four carbons, carbon one has three hydrogens, carbon two has one hydrogen and a carbon, which has three hydrogens, carbon three has two hydrogens and carbon four has three hydrogens. The third (dimethyl propane) is a chain of three carbons in which the two end carbons have three hydrogens each and the middle carbon has two adjacent carbons, each with three hydrogens.

1) I could draw four isomeres with a few variations on the last one. The first is a line of five carbons surrounded by H. Next is a Central C with four C's attatched to it. Each of the four outer carbons have H's attatched to them. Then there is a vertical line of three carbons with two more attatched horizontally to the central Carbon with H's around each one. Finally one could line four C's up with a single carbon coming of of the string perpendicularly. H's would be surrounding each carbon. This structure could be varied depending on which carbon the ether group was attatched to. I'm sure there are a ton of other isomers and I racked my brain, but I couldn't come up with any more for the life of me.

I drew 6 isomers. The first isomer was a link of 5 carbons together with two hydrogens attached to the three middle carbons and three hydrogens attached to the two outter carbons. The next 4 isomers have a link of 4 carbons with the fifth carbon branching out from one of the other 4 carbons. Since there are 4 different carbons the fifth can be attached to, there are 4 different isomers. The 3 carbons not connected to the fifth are all surrounded by hydrogens and the fifth carbon is surrounded by 3 hydrogens. The last isomer was a single carbon in the middle with 4 carbons branching out from it. Attachted to each of the 4 carbons are 3 hydrogens apiece.

I was able to come up with four very distinct structures, with about 20 variations on those structures. The first and simplest structure is a 5 carbon chain, with hydrogens taking up the rest of the free bonds. My second idea was a 3 carbon chain with a two carbon chain coming off of it. This second chain could go in one of two directions from three different carbons, giving us six possibilities. A third structure would be a 3 carbon chain with two carbons attached, separately forming metyl groups, to the chain. I calculated 9 different combinations this way, with hydrogens filling in the additional bonds. One other possibility is a four carbon chain, with the fifth carbon coming off of one of the four carbons, forming a methyl group. I also experimented wih 3- 4- and 5-carbon rings, but none of those panned out as a possibility.

I drew 7 molecules. The first was a 5-carbon chain with two hydrogens attatched to the three central carbon atoms and three hydrogens attatched to the two outer carbon atoms.

The second was a cross-shaped molecule with a carbon in the middle, bonded to four other carbons, each of which had three hydrogen bonds. The third molecule was a four-carbon chain with the second carbon bonded to (besides two carbons in the chain) another carbon and a hydrogen. The three outer carbons were bonded to three hydrogens each.

The next 2 molecules were 3-carbon chains with carbons bonded to two of the chain members. Each molecule varied its pattern. One end carbon was bonded to 3 hydrogens and the other end carbon was bonded to 2 hydrogens and a carbon. The center molecule was bonded to one hydrogen and one carbon. The two outer carbons were bonded to 3 hydrogens.

The sixth molecule was similar to the last 2, but the middle carbon was bonded to 2 hydrogens and the outer carbons of the 3-carbon chain were bonded to 2 hydrogens and a carbon (each of which was bonded to 3 carbons).

The final molecule was a tetrahedron with a carbon center bonded to 4 other carbons, each of which was bonded to 3 hydrogens.

Not Counting mirror images I could come up with about 4 different isomers, and from each of those I could the mirror image, except for the hydrocarbon chain that has no mirror image. So first of all I got the hydrocarbon chain: The 5 carbons each 3 with 2 H off of them and the ends with 3. Then I got the one with 3 carbons across, and a carbon coming off of the end C. The Protruding C have 3 H attached and the 3 central C only have 2. Then there was the Tetrahedral shaped structure. With a central C bonded to 4 other C, each with 3 Hydrogens coming off of it (Distel saw this one, I think he thinks more spacally than I do). Also I got the planar version of this which is cross shaped, and designed the same way, so I guess that is really the same one just differently arranged. I couldn't get any double bonds to work out, because I either had two many H, or not enough C to go around. For the same reason the triple bond didn't work out.

I came up with 6 different isomers. The first one is with a Carbon chain with a Hydrogen attached all around it. The second is a central Carbon with the other 4 Carbons radiating off. Off of these Carbons there are 3 Hydrogens surrounding them. The next one is a 3 Carbon chain with a Carbon attached to the top and the bottom of the first Carbon with the Hydrogens filling other spaces. A 4 Carbon chain attached to one of the Carbons and the Hydrogen around the Carbons where they fit. This same idea can be used by moving where each Carbon is placed off the 4 Carbon chain. A bent chain of Carbon can be made, but it can't be all connected, then the Hydrogens can surrounding the others. Overall I found many isomers, by changing the position of where the Carbon is linked off.

I was able to draw 23 strustures. For each structure, Carbon has four bonds. Any bond that is not C-C, assume to be the Hydrogen.

1. a chain of 5 Carbons in a row, H's circling

2. chain of 4 carbons, the 5th C branching up from the 2nd C

3. chain of 4 C's, 5th C branching down from the 2nd C

4. chain of 4 C's, 5th C branching up from the 3rd C

5. chain of 4 C's, 5th C branching down from 3rd C

6. chain of 3 C's, a C branching up from the 2nd and 3 C

7. same as #6, but branching down

8. chain of 3 C's, a C branching down from the 1st and 2nd C

9. same as #8, but branching up

10. chain of 3 C's, a c branching down from the 1st and 3rd C

11. same as #10, but branching down

12. chain of 3 C's, 2 C's branching down from the 1st C

13. same as #12, only branching up

14. chain of 3 C's, 2 C's branching down from the 2nd C

15. same as #14, only branching up

16. chain of 3 C's, 2 C's branching down from the 3rd C

17. same as #16, but branching up

18. chain of 3 C's, 1 C branching up from the 1st and 1 down from the 2nd

19. chain of 3 C's, 1 C branching up from the 1st and 1 down from the 3rd

20. chain of 3 C's, 1 C branching up from the 2nd and 1 down from the 3rd

21. chain of 3 C's, 1 C branching down from the 1st and 1 up from the 2nd

22. chain of 3 C's, 1 C branching down form the 1st and 1 up from the 3rd

23. chain of 3 C's, 1 C branching down from the 2nd and 1 up from the 3rd

I found three main isomers using C5H12. They are:

1. A chain of five carbons surrounded by the remaining twelve

hydrogens. This is called Pentane.

2. A chain of four carbons with the fifth carbon attached to the

second carbon in the chain. This is called 2,methyl butane

because the methyl is connected to the second carbon in the butane

sequence.

3. A chain of three carbons that has a carbon attached to the “top”

and “bottom” of the second carbon in the chain of three. This is

called 2,2dimethyl propane.

4 structures

1. chain of 5 carbons

2. chain of 4 carbons with a CH3 grouup off of one of the inside carbons

3. chain of 3 carbons with CH3 groups off of an outside and the middle carbons

4. a central carbon surrounded by 4 CH3 groups

1. A 5-Carbon chain surrounded by hydrogen.

2-5. A 4-Carbon chain with a carbon above one of the other four carbons. All carbons surrounded by hydrogen.

6-9. A 4-Carbon chain with a carbon below one of the other four carbons. All carbons surrounded by hydrogen.

10-12. A 3-Carbon chain with the two remaining carbons above two of the three carbons (e.g. above carbon 1 and carbon 2; above carbon 1 and carbon 3). All carbons surrounded by hydrogen.

13-15. A 3-Carbon chain with the two remaining carbons below two of the three carbons. All carbons surrounded by hydrogen.

16-24. A 3-Carbon chain with one carbon above the chain and one carbon below the chain (e.g. above carbon 1 and below carbon 1; above carbon 1 and below carbon 2, etc.) All carbons surrounded by hydrogen.

I could only draw around ten isomers of C5H12. Most are variations of a line structure with alternating methyl groups, and one ringed structure. A couple had a three carbon base with one methyl group at each end on alternating sides. One was tetrahedral and one was trigonal planar. I am trying to think of more variations, and I know I am missing a few, but nothing seems to work out. I have trouble with isomers for some reason. If we could work on them more, I would greatly appreciate it. I guess we will have to see if the rest of the class has trouble or if I am just isomerically impaired. :)

The are three isomers of the hydrocarbon containing five carbons and twelve hydrogens. The first is a continuous chain of five carbons. The first is connected to the second. The second is connected to the first and third. The third is connected to the second and fourth etc. Three hydrogens are bonded to each of the end carbons and two hydrogens are bonded to each of the three remaining carbons. The second isomer consists of four carbons in a row with a fifth carbon bonded to the second carbon in the chain. The second carbon also has one hydrogen bonded to it. The two end carbons and the one bonded to the second carbon each has three hydrogens. The remaining two are bonded to two hydrogens each. The third isomer consists of a central carbon bonded to four other carbons. The central carbon is bonded to no hydrogens. Each of the other four is bonded to four hydrogens.

I thought I had drawn 7, but when I showed them to Aaron Harnar he informed me that I only had three because of the tracing carbon with a pencil rule. One looks like two mountains of connected carbons with hydrogens surrounding them. The second one looks like a cross of carbons also with the hydrogens surrounding the carbons. The third one looks like a upside down v of carbons with a carbon flag on top and the surrounding hydrogens.

There are 5 different isomers of C5H12. The first one is a straight chain of the five carbon atoms, each surrounded by hydrogen to give each carbon four bonds. The second is a chain of four carbon atoms with a CH3 group off the second C atom. The third is a chain of four carbon atoms with a CH3 group off the third C atom. The fourth is a chain of three carbon atoms with two CH3 groups off the first carbon atom. A mirror image (two CH3 grops off the third C atom) can also exist. The fifth isomer is a chain of three carbon atoms with two CH3 groups off the center C atom. Other arrangements, such as a chain of four C atoms with a CH3 group off the first C atom, can be treated as a straight chain.

I drew five isomers for C5H12, but there are more that can be derived from these five. Each Carbon is surrounded by four bonds, be it to another Carbon, or a Hydrogen.

a) c-c-c-c-c This is a straight chain of five Carbons. However, there can be a kink or many kinks in the chain of Carbons, but this structure is still one Carbon bonded to a maximum of two other Carbons.

b) Off of the second Carbon in a straight chain of four Carbons is a methyl group. This methyl group may also be off of the third Carbon, reading from left to right in a straight chain of four Carbons. These methyl groups may be linked either above or below the Carbons it is bonded to. Therefore it is a link of four Carbons with three linked Carbon to Carbon, and one linked to three Carbons. These isomers may be considered to be the same in structure with simply different locations around the chain of Carbons.

c) In a straight chain of three Carbons, a two Carbon chain linked onto the second Carbon, again either above or below the Carbon in the three Carbon chain.

d) Here the Carbons form a cross. In a straight chain of three Carbons, a methyl group coming off of the second Carbon in two directions, on paper one up and one down.

e) In a straight chain of three Carbons have a methyl group come off either the first or the last Carbon in two directions, again on paper one up and one down. These structures may be considered to be the same.

I came up with with four isomers. The first drawing has all the carbons linked together in a single chain (5 carbons in a row) with hydrogens surrounding it. The second isomer is similar to the first except the carbon at the end is linked to the third carbon in the row, and hydrogens also surround the carbons. The third structure has the carbons linked together in the form of an addition sign with hydrogens surrounding the carbons. And finally, the fourth drawing has three carbons linked to one another in a row and two carbons linked together to the middle of the three carbons This also has hydrogens surrounding the carbons.

three.

(1) all 5 carbons line up linearly.

(2) one carbon is center and other four sround it.(the center one connected with 4 carbons)

(3) four carbons form linear and the other bond with the second/third one.

2 straight lines of C, one verticle, one horizontal with H off of

each C.

One Cross of Cs with H off the 4 noncentral Cs.

4 Ts, one upright, one upside down, one to the right and one to the

left with Hs

4 Ls, again positioned like the Ts with Hs filling all open C bonds

4 off center Ts two upright, two upside down, with H off the Cs

(I hope you understand what I'm trying to describe. All single

bonds, no dbls)

Three isomers can be drawn from C5H12. The first isomer is a five-carbon chain with three hydrogens bonded to the end carbons and two hydrogens bonded to the other carbons in the chain. I believe this isomer is called pentane. The second isomer is a four-carbon chain with the fifth carbon bonded to carbon #2. In this isomer the end carbons of the four-carbon chain are bonded to three hydrogens and carbon #3 is bonded to two hydrogens. The second carbon however is bonded to the fifth carbon and one hydrogen, and finally the fifth carbon is bonded to three hydrogens. I believe that this isomer is called 2,methyl butane. The third isomer is a three-carbon chain with carbons #4 and 5 bonded to the middle carbon in the chain. The end carbons in the chain are bonded to three hydrogens and the 4th and 5th carbons are bonded to the middle carbon and to three hydrogens. I believe that this isomer may be called 2,2 dimethyl propane.

I came up with three isomers for the given molecule. I'm going to try to attach a file to try to better illustrate my work. However, I'll give you a verbal description as well(computers. . . you just never know). The first isomer is a straight chain of 5 carbons (C-C-C-C-C) surrounded by hydrogens (two atoms per cabon) and one hydrogen on either end of the chain. The second isomer is a cross composed of the five carbon. In this case, the middle carbon is bonded with the four other carbons, and each outer carbon has three Hydrogen molecules. The third isomer is very similar to the first, straight-chain isomer, except one of the carbons is not in the straight line. It is instead attached to one of the carbons in the chain, forming a sort of branch off of the main line. This branched Carbon will have three hydrogen attached to it, as will both the end carbons. The center carbon (the one attached to three other carbons), with have only one hydrogen. The other middle carbon will have only two hydrogens attached to it.

2.

The signal for a carbon attached to a nitrogen would be approximately 30 ppm. This is because nitrogen has a greater elecronegativity than silicon or carbon, but less than oxygen. Thus, the signal would fall between that of carbon and oxygen.

The attachment would come at about 20-25 ppm. This is so because the electron density would be more than a carbon attaching to another carbon and less than a carbon attaching to an oxygen because the dipole (N) is in between the C and the O so its electron density would be in the middle as well. Atomic weight has a big deal as the number of electrons affects the electron density as the carbon attaching to the nitrogen would be somewhete in between the other two bonding because of the number of electrons in the valence shell.

I would expect the value for nitrogen attached to carbon to lie between 15 and 50, most likely around 40 or so. The explanation for this is based strongly on differences of electronegativities. Nitrogen is less electronegative than oxygen. Therefore, the dipole moment between the carbon-oxygen bond is greater than the dipole moment between the carbon-nitrogen bond. However the dipole moment between the carbon-carbon bond is less than the dipole moment between the carbon-nitrogen bond. The electron density is greater around the more electronegative atom in the bond because it is pulling harder for the electrons. Because oxygen is the most electronegative it is pulling the hardest compared to the carbon it will have the largest value representing the greatest electron density. Nitrogen is only slightly less electronegative in comparison to oxygen so it will have only a slightly smaller electron density, reflected in an only slightly smaller value.

I believe that it would come somewhere between 15-50ppm. I feel this way because Nitrogen in placed between Carbon and oxygen on the periodic table. Due to the placement of the electrons on Nitrogen compared to carbon and oxygen it should fall somewhere between those two limints. I couldn' narrow that scope down any further though because I don't fully understand this concept yet.

I think it will be arround 30 or 35 ppm because Nitrogen has one less valence electron than oxygen and one more valence electron than carbon so it will be in the middle of the two signals.

The signal should be between 30-35 ppm, because that is halfway between the value for carbon-carbon and carbon-oxygen. Nitrogen is between carbon and oxygen.

Between 20 and 25 ppm because nitrogen's polartiy is between the polarity of carbon and the polarity of oxygen.

I would imagine the Nitrogen-Carbon bond would have a signal between 15-50. This could be right around 30 or so give or take 5-7ppm either way. I think that it would give this type of reading because carbon has less available electrons to be emitted on the C-13, than Nitrogen and thus a lower signal, but O has more than C and so gives a higher signal. Also Nitrogen is in between the two interms of reactivity, so should be proportionally between them. As for why silicon has such a low, I think that has to do with its transition metal catagory, and being in a different period, but I don't know exacty why that would effect it, because the whole C-13 spec is new to me.

The value would range from 20 to 25. This based on the fact that there is 0 ppm for Silicon, which is in the same period. The oxygen is two periods over has more electrons in the outer shell.

Electronegetivities increase from left to the right on the periodic table. Since nitrogen is further right than carbon but to the left of oxygen, the electron density would be greater than 15 ppm, but less than 50 ppm. (I used my text and the periodic table to solve this.)

A carbon attached to a nitrogen would occur somewhere between 15ppm

and 50ppm. This is caused because of the difference between the

electronegativities.

THe signal would be somewhere between 15 and 50, closer to 50 because the electronegativity of nitrogen is high but not as high as oxygen.

A carbon attached to nitrogen would come somewhere between 15 ppm and 50 ppm because the size of nitrogen is larger than carbon, yet smaller than oxygen.

A C-N signal would most likely fall in the range 15ppm to 50 ppm. Nitrogen would create a larger dipole than C but a smaller dipole than O. The charge on the N atom is in between the charge on O and the charge on N therefore causing the mentioned CNMR range.

The ppm values for silicon bonded to carbon, carbon bonded to carbon, and oxygen bonded to carbon were plotted on a graph with their respective electronegativities. These three points were connected with a smooth, curved line to produce a graph. This graph was then used with nitrogen's electronegativity to estimate what the ppm value for nitrogen bonded to carbon would be. The result suggested that a nitrogen bonded to a carbon would have a ppm value near 27.5.

I would expect the nitrogen to be halfway between the carbon and the oxygen values (~32.5ppm). I arrived at this by comparing the electronegativity values. Since I know that electronegativity impacts the way electrons move and that in turn it changes where the electrons will be I used those values to predict the approximate electron density. The electronegativity value for nitrogen (3ppm) is halfway between carbon (2.5ppm) and oxygen (3.5ppm). I checked this answer with Aaron and he seemed to agree.

A carbon attached to a nitrogen would fall between 15 ppm and 50 ppm. This is because oxygen has a higher electronegativity, and thus a larger dipole and a larger change in electron density. Carbon is less electronegative, and has a smaller change in electron density. Nitrogen falls in between carbon and oxygen in electronegativity, so it would also fall between them in changes in electron density.

The signal for a Carbon-Nitrogen bond would come between 15 and 50 ppm. The electrostatic difference between a Carbon and Nitrogen bond falls between the values of the electrostatic difference between a Carbon to Carbon bond and a Carbon to Oxygen bond. Thusly the signal would also fall between those two signal values.

The nitrogen would be between 15ppm and 50ppm. The electron density of nitrogen is larger than carbon yet smaller than oxygen because of the order of those elements on the periodic table. Carbon comes before nitrogen, which comes before oxygen. The dipole and electron density get larger when moving from left to right of the periodic table.

between 15 and 50ppm.

the difference of electronegativity of C and O is 1.0. That of C and N is 0.5. and C-C is 0. C-Si is 0.7. At this point, the electron density and the difference of electronegativity does not seem to have relationship. so I'm really not sure...

The the bond length C-C is longer than C-N and C-O. C-N is longer than C-O(from text). since the difference of electronegativity between them is reverse order( C-C one is smallest). So I guess i can say that longer distance and weak polar cause smallest electron density. so the order of electron density would be C-C smallest, C-N,C-O largest. so the value will be between 15 and 50ppm.

I am not sure if I can explain with electronegativity especially difference between C-C is 0.

Since the signal is dependent on electron density and e- density is

related to

electronegativity, carbon and nitrogen would give a signal

somewhere between

15 and 50 because nitrogen is less electronegative than O and more

than C.

A carbon attached to a nitrogen would fall between 15 and 30ppm or between carbon-carbon and carbon-oxygen. This is because nitrogen’s electronegativity is smaller than oxygen’s but a larger than carbon’s. Nitrogen’s electronegativity is closer to that of oxygen than carbon so it would lie closer to 50 than 15ppm. The difference in electronegativity between the two atoms determines the strength of the dipole moments of the atoms. The greater the difference in electronegativity the greater the dipole moment is between the two atoms. For example the atom with the greater electronegativity would attract the electrons with a stronger force, causing the dipole moment to become more influential on that atom. From the established data given in this question, as the difference in electronegativity increases so does the measure of ppm for that attraction.

I predict that a carbon attached to a Nitrogen would come in at about 30 ppm. Since the position of the signal was dependent on the electron density around the carbon, I came to this conclusion by studying the differences in electromagnetivity between the carbon atom and the other atoms. Silicon is less electromagnetive than carbon, and perhaps for this reason falls below registering. Oxygen is more electromagnetive than Carbon, and therefore has a higher reading than that of carbon attached to carbon. Nitrogen has an electromagnetivity of approximately 3.0; higher than carbon and lower than oxygen. After constructing a rough graph of readings versus differences in electronegativity, I found that Nitrogen's electronegativity may put a reading near 30 ppm.

3.

l – b

21 – c

2 - d

The answer is c. the m/z represents the mass to charge ratio. The charge in most cases is 1. therefore the m/z usually represents the molecular weight of the molecule. The empirical weight is approximately 14g. 56 is the fourth multiple of this number suggesting that the subscripts be multiplied by four and give us the answer of C₄H₈.

4. comments

Any possibility of you going over the stuff in the second half of chapter two spectroscopy?

The only thing I’m confused about is in number two. Although I understand the concept of the electronegativities and dipole moments, I’m afraid I don’t have an explanation for the silicon-carbon bond value being 0, or the fact why carbon-carbon would even have a dipole moment. I am fairly confident that my explanation is valid, but I cannot account for that.

Acknowledgements:

Assistance from Becca Fredrick, Todd Young, Katie Palof, and Jen Fraifogle.

I really hope that you arent grading this warmups very hard becuse this kind of learning doesn't work for me very well. I need to talk to someone who knows how to do these problems for sure, because if I just try to beat my way through to the correct answer I end up second guessing myself. This uneasyness about my ability to find the correct answer usually continues through the time it has been explained to me the correct way and I end up being too unsure of my own abilities.

I am very unclear on a bunch of concepts and the spec reading seemed to be over my head in a lot of places. The ring structures on pg 3 of the spec book confused me as to how they appled the 2n +2 formula to them and arrived at the right answers in constructing the carbon ring sequence. Also does the 2n + 2 give the # of hydrogens?. What is the base peak, and how does that help us understand the others? And what are the M+, R+, B+, ect labels? What do they stand for, mean, relate to? I was just very lost at the end of chapter 2 of the reading and I had difficulty straightening out what was useful and what was just above me.

But hopefully with time.

Thanks and as soon as we can get some clearity on these i will be greatly apprieciative.

I don't understand what resonance structures are on page 16 of the text.

I also don't understand the counting method/ not crossing lines thing (page 3 of Spectroscopy book) used to determine degrees of seperation.

I an not sure that I named the isomers correctly in the first question but I hope that I described them well enough for you to understand them. Also, in the second question I understand why nitrogen would fall where it does but I do not understand how the measurements of ppm relate to what is being measured in the experiment. For example, why does the carbon-carbon bond come out 15 ppm, when carbon-carbon is equal?

Acknowledgements: Jen Fraifogl, Lauren Bell, Todd Young, and Becca Fredrick.

I really hope we can go over question number two. I spent a great deal of time trying to get my brain to unwrap that one! Also, will we need to know how to determine the vector magnitude of dipole moments?