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Chemistry 2050 Introduction to Organic ChemistryFall Semester 2004, Dr. Rainer Glaser

Examination #1“Bonding, Alkanes, Alcohols & Alkyl Halides”

Questions 1 - 3: Wednesday, 9/29/04, 11 – 11:50am.Questions 4 & 5: Submit Friday, 10/01/04, 11am.

Name:

Answer Key

Question 1. Carbon Basics. 20Question 2. Atomic Structure, Lewis Structures & Bonding 20Question 3. Alkanes, Haloalkanes, and Alcohols 20Question 4. Looking for the Hydrogen Horizon. 15Question 5. Toxicity of C60. 25

Total 100

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Question 1. Carbon. (20 points)

(a) How many C-atoms in the most famous buckyball? _____60_____. (1 point) Buckyballs havetwo kinds of rings: _6_-membered rings and _5_-membered rings. (2 points) Why are “buckyballs”called that way? (2 points)

Buckminster Fuller, architect of geodesic domes

(b ) Let’s draw a piece of a sheet ofgraphite. The sigma bonds are shown forone ring and all the rings that surround it.Add double bond as needed. There aremany possible ways to draw the doublebonds; draw one way that makes sense.Each C-atom has _1_ electron(s) in its p-type atomic orbital. (5 points)

and others

(c) Explain why these C-tubes are called “nanotubes”. What is “nano” about these tubes? (5 p.)

1 nm = _____10____ Angstroms

1 nm = ____1,000___ pm

Length of a C-C single bond: __154_ pm

Explain (2 p.):

Dimensions are in the nanometer range.Ten C-C single bonds make 1.54 nm.

(e) Diamond contains C atoms that are _sp3_-hybridized. All carbon atoms are surrounded by __4_(give number) C atoms. The geometry at every C-atom is __tetrahedral____. Diamond _______(does, does not) contain double bonds. Diamond ________ (does, does not) conduct electricity.Diamond contains ___6_-membered rings and the rings _________ (are, are not) planar. The closelyrelated modification “hexagonal diamond” is known as ____Lonsdalite___. (5 points, -1 for each error)

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Question 2. Atomic Structure, Lewis Structures & Bonding. (20 points)

(a) A neutral carbon atom has __6_ protons, __2_ core electrons, and __4_ valence electrons. In the leftbox, complete the electron configuration of a neutral carbon atom by provision of the exponents (e.g. thenumber of electrons in that AO). In the right box, draw the valence electrons as “arrows”. (5 points)

1s2 2s2 2px1 2py

1 2pz0 ↑↓ ↑ ↑ __

(b) Draw the complete Lewis structures (all atoms, all bonds, all lone pairs, draw all pairs as dashes, usedots only for unpaired electrons, indicate formal charges if any). (5 points)

Carbon dioxide, CO2

O C O

Nitric Oxide, NO

N O

(c) Draw all resonance forms of HNO3. Draw the “resonance arrow” between the structures. Drawcomplete Lewis structures. (5 points)

O

NO O

HO

NO O

H

(d) The most abundant carbon isotope has mass _12_ and about _1.1_% of carbon in nature is theisotope with mass 13, 13C. In contrast, the abundance of 14C is very, very small and only about 1 in____a billion___ (103, 106, 109). The isotope 14C is radioactive and decays with a half-life of roughly__5,700__ years. The oldest materials at Stonehenge (http://www.c14dating.com/applic.html) are about5,000 years old; that is roughly about _50_ % of the original of 14C content is left. (5 points)

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Question 3. Alkanes, Chloroalkanes, and Alcohols. (20 points)

(a) Nomenclature. Draw the complete structureof 2-chloropentane; draw every atom, everybond, every lone pair. (2 points)

H3CCH

CH2

H2C

CH3

Cl

Give the IUPAC name of the structure shown. (3points) Name: 3,3,4-trichlorohexane

ClCl

Cl

(b) Consider the combustion of propane, C3H8. Provide a stoichiometric reaction equation for theoxidation of propane with O2. Which oxidation reaction drives “normal” fuel cells? Provide astoichiometric reaction equation. Propane Combustion (3 points): H3C−CH2−CH3 + 5 O2 3 CO2 + 4 H2O

Fuel Cell Reaction (2 points): 2 H2 + O2 2 H2O

(c) Tertiary butanol (CH3)3COH is treated withHCl. Draw the product of the____unimolecular____ ____nucleophilic_________substitution___ reaction, or SN1 for short,and name it. (5 points)

Cl

H3C

H3CH3C

(d) When methanol is treated with HCl, the firststep of the reaction consists in the protonation ofmethanol. Draw the product of this protonation.Show all atoms, show all lone pairs, show formalcharges. (5 points)

H3C O

H

H

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Chemistry 2050 Introduction to Organic ChemistryFall Semester 2004, Dr. Rainer Glaser

Examination #1“Bonding, Alkanes, Alcohols & Alkyl Halides”

Questions 1 - 3: Wednesday, 9/29/04, 11 – 11:50am.Questions 4 & 5: Submit Friday, 10/01/04, 11am.

Name:

Question 1. Carbon Basics. 20Question 2. Atomic Structure, Lewis Structures & Bonding 20Question 3. Alkanes, Haloalkanes, and Alcohols 20Question 4. Looking for the Hydrogen Horizon. 15Question 5. Toxicity of C60. 25

Total 100

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Question 4. Toward the Hydrogen Economy. (15 points)

Tuesday, 21 September, 2004, 10:49 GMT 11:49 UK

Looking to the hydrogen horizonBy Paul Mason

BBC Newsnight business correspondent

Demand for oil is soaring, and with it the price - currently $46 a barrel.

Discoveries of new reserves are getting thinner and the cost of production is rising, especially inthe older fields.

Some believe we are reaching the beginning of the end of the oil epoch. But, they say, hydrogencars could offer a route out of the problem.

Hydrogen technology is not new but the millions of research dollars spent in recent years mayfinally realise the potential, some experts believe.

Price crunch

"It's not a question of oil running out," says environmental campaigner George Monbiot.

"There will always be dregs stuck in the ground. But if demand exceeds supply as costs ofextraction rise, we will see a very serious price crunch."

In the year 2000, total demand for oil was 3,604 million tonnes, according to the InternationalEnergy Agency.

In the richest countries, transport accounts for the biggest share, with industry and powergeneration dominant among the other uses.

In the developing world, there are fewer cars, so oil for transport is less important. But by 2030,the picture will have changed.

World demand will be 5,769 million tonnes, and, while the rich countries will be using an evenbigger proportion for transport, the poorer countries' oil profile will look like ours does now. And itis all because of humanity's love affair with the motor car.

Cars driven by hydrogen-powered fuel cells are the much trumpeted solution.

Fuel cells turn the chemical energy stored in the hydrogen into electrical energy which drives thecar. There are now several test vehicles working the open roads.

The SiGen mini I looked at recently drove like a cross between a dodgem and a Robin Reliant - butthen it was just a cheap model converted to prove the concept.

The company behind the car is run by former North Sea oilmen who have seen the writing on thewall.

"Looking at field data, it was clear we were facing very serious problems with hydrocarbonproduction," says David McGrath, SiGen's managing director.

"There might be oil in the ground but we're not going to be able to produce it fast enough to meetdemand. Something has to give. We saw hydrogen fuel-cell technology as an opportunity todisplace fossil hydrocarbons - albeit very slowly, but progressively."

"The future is hydrogen"

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Until the late 1990s, the big car companies dismissed the idea of fuel-cell engines. They do notanymore.

"Ford and other manufacturers agree the future is hydrogen," says Pete Pethers, director of Ford'svehicle environmental engineering department. "It's not a question of what the fuel is in the future;it's a question of the pace of change.

"We have to address the infrastructure issues; our customers have to be able to purchase this fuelto refuel their vehicles. And we also have to address the very fundamental concern of accessingthis hydrogen from renewable sources, such as solar and wind.

"The next phase of the Ford programme in 2007 will be to put greater quantities of these vehiclesout into the market place to prove our technology, to prove there are no durability issues. If youare looking at when you could buy a fuel-cell car, you're looking at the 2010-12 timescale."

Although at the users' end hydrogen may appear abundant (it is in the H20 of seawater) and clean(zero emissions), at the producers' end, things are not so straightforward.

What is the most efficient and cleanest way to split the water? Should we use nuclear andrenewable sources, such as wind and waves, to isolate the hydrogen? Or should we take thehydrogen out of fossil fuels? The hydrogen lobby cannot agree.

Freedom Car

Last year, on the eve of the invasion of Iraq, President Bush announced a $1.2bn researchprogramme into hydrogen fuel technology. Labelled the Freedom Car, the Bush plan sees 90% ofthe hydrogen coming from fossil fuels, with the other 10% from nuclear.

Sustainable energy is dismissed as too expensive. The men who put together the SiGen vehiclethink otherwise.

"If we were to exploit renewable energy resources around the UK - the UK has the highest level ofrenewable energy concentration in the whole of Europe - we could dramatically decrease ourdependence on import of fossil hydrocarbons; and have a big impact on environment and on thebalance of payments," believes David McGrath.

If we really are approaching the end of the oil age, the biggest problem facing the transition is theexisting infrastructure - the pipelines and petrol stations worth an estimated six trillion dollars.

Writing this off would require an economic revolution much bigger than the one Henry Ford started.

"Energy transitions take a long time," says Dr David Hart, from the department of environmentalscience and technology at Imperial College London.

"It's clear to see from the longevity of a Routemaster bus, for example, that once something is putin place that works well, it's difficult to change it.

"So, hydrogen transition is more a 50-year solution to the end state. That doesn't mean thatsomewhere along the road, in 10-15 years from now, we won't have a significant amount of energythat can be used from hydrogen.

"What we are likely to see is a much more decentralised system of energy production anddistribution. At the moment, energy is produced centrally and is transported over very longdistances over very large infrastructures.

"We are likely to become personally much more involved in energy in the future. We are likely tohave things attached to our vehicles and our houses to cushion us as we move away from theselarge, centralised schemes."

But to start the transition to a hydrogen economy, it is not enough to put public funds intoresearching the technology, believe campaigners.

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"There has to be a clear policy signal given to consumers and companies alike. Governments wouldhave to say, "the oil age is coming to an end and we're going to create the policy framework tomake it profitable to build the new infrastructure".

"If the economy is going into recession, if the oil price keeps rising - the time to invest in all this isnow," argues George Monbiot.

"But political pressure for the investment in the re-engineering of our cities and infrastructure, itisn't there yet. People don't riot for austerity; they riot because they want more, not less. We haveto riot for less."

Story from BBC NEWS:

Question 4. Toward the Hydrogen Economy. (15 points)

(a) What was the total demand of oil in the year 2000? Give number and units! How much is the totalreserve (in all the world combined) that can be recovered economically. Give number and units! Howlong could we go on the way we do right now if the demand stays the same and if those reserves actuallyexist? (5 points)

Total Demand in 2000, from text: 3,6 million tonnesTotal Reserve in 2002, from graph: about 1,000 billion barrels = 125 million tonneshttp://www.schoolscience.co.uk/content/4/chemistry/petroleum/knowl/4/2index.htm?oilcost.htmlWeight of a barrel depends on kind of oil. There are about 8 barrels in a tonne.Enough oil to sustain status quo for 35 years. You will live twice that long; you HAVE a problem!

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(b) Propose YOUR very own plan for the generation of hydrogen fuel. Your answer might depend onwhere you live and, in the context of this question, you can assume any nationality you’d like. Say whatresource you would use and where the energy would come from to generate the hydrogen from thatresource. Your plan can have several components. Provide reasons for the choice you made. Yourreasons can be “reasons for your solution” and your reasons also can include “reasons against analternative”. Be thoughtful; your response will be graded by Ms. Kathleen Carson. (10 points)

I am answering this question as a citizen of _____________:

Many answers are possible:

1. Germany: a) Will buy electric power in Russia and use the electricity to make hydrogengas from water by way of electrolysis. b) German chemical companies will develop catalysts toconvert imported biomass into hydrogen gas. c) With federal support, Mercedes andVolkswagen will develop the “perfect hydrogen combustion motor” with the highest possibleefficiency. d ) Michael Schumacher wins the F1 world championship 2011 in a redFerrari/Volkswagen with an H-V12 engine.

2. Russia: a) Builds bank of nuclear reactors in remote Siberia and defend the area withmighty military against terrorist. b) Use new carbon nanotube technology to deliver cheapelectricity to Europe and China. c) Generate hydrogen gas by electrolysis using Germantechnology.

3. USA: a) Focus on farming renewable biomass in Midwestern states. b) Use private sectorto develop efficient catalysts to convert biomass into hydrogen gas and “soy-plywood” buildingmaterials for annual re-construction of post-hurricane South (Florida to Louisiana).

4. France: a) Build nuclear reactors for use at home and for export. b) Claims “superiorhydrogen quality” since French hydrogen gas is generated by electrolysis of Perrier.

5. Saudi Arabia: No plans. Will limit oil export and seek the world’s remaining superpowermilitary protection in exchange for satisfying their oil needs as well.

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Question 5. The Tiny Death? (25 points)

(a) In the article, the authors provide concentrations in units of “ppb”. This is a so-called particledensity. What does “ppb” stand for? (1 p.). Assume that there are 300 million Americans. What isyour particle density within this population? (If there is only one Bill Mill in the US, what is Bill Mill’sparticle density among all Americans?) Show work, provide number correct to 3 digits. (2 p.)

ppb === parts per billion [parts]I am one part in 300 million [parts]I “am” X parts in 1 billion [parts] Bill Mill’s particle density is 3.333 ppb

(b) It is reported that the buckyballs generate “superoxide anions” andthat these superoxide anions damage the cells. Draw the complete Lewisstructure of “superoxide anion”. (2 points)

O O

(c) C60 is said to be “sparingly soluble” in water. The term “sparingly soluble” is not useful; the termprovides very little information. Go to the original research article and find out what the solubilityactually is. Provide the number with units and provide the complete citation of the source (in ACSformat!) where you found that number. (6 points)

Nano-C60 solubility is given as 50 mg/L on the first page of the paper.

The Differential Cytotoxicity of Water-Soluble Fullerenes Sayes, C. M.; Fortner, J. D.; Guo, W.;Lyon, D.; Boyd, A. M.; Ausman, K. D.; Tao, Y. J.; Sitharaman, B.; Wilson, L. J.; Hughes, J. B.;West, J. L.; Colvin, V. L. Nano Lett. Web Release Date: 11-Sep-2004

(d) The C60 molecules do not dissolve well in water. Explain why that is so. In particular, state whetherC60 would like/hate to be dissolved in water and whether water would love/hate dissolving the C60. Youalso should say something as to what “love” or “hate” means in this context. (6 points)

C60 molecule with C60 molecule: temporary dipole induces dipoleH2O molecule with H2O molecule: special permanent dipole and permanent dipole: H-bondingC60 molecule with H2O molecule: water permanent dipole and induced dipole of C60

C60 molecule would love it! Water would hate it! Will not happen!

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(e) Nano-C60 is said to form colloids in solution. “Colloid” is a new term; what does it mean?Indicating each C60 schematically as a circle with a diameter of about an inch, draw a cartoon of acolloid of ten C60 molecules floating around in water. Draw complete Lewis structures of at least tenwater molecules around the colloid. Draw the water molecules to scale as much as possible. Thinkabout their preferred orientations with regard to each other and with regard to the buckyballs. (8 points)

OH

H

OH

H

OH

H

OH

H

OH

H

OH H

OH H

O

H

H

O

H

H

O

H

H

OH HO

H

H

OH

H

OH

H

O HH

O H

H

OH

H

OH

H

OH

H

O

H

H

O

H

H

OH

H

OH

H

O

H

H