Solution manual for chemistry human activity chemical reactivity 2nd edition by mahaffy

1.6 Non-medical applications of light-absorbing porphyrins include their use in rewriteable CDs and DVDs, in making inexpensive electrodes for fuel cells, and as catalysts to produce am

Human Activity, Chemical Reactivity

REVIEW QUESTIONS

Section 1.2: Harnessing Light Energy and Exciting Oxygen

1.1

PDT or photodynamic therapy requires a photo sensitizer, light, and oxygen The photo sensitizer

is a molecule that readily absorbs light, and transfers its extra energy to neighbouring triplet

oxygen (the usual form of oxygen found in tissue and elsewhere) The transferred energy takes

triplet oxygen to its singlet state The very reactive singlet oxygen kills rapidly growing cancer

cells

1.2

Yes However, a different photosensitizer would be required—one that primarily absorbs green

light rather than red light

1.3

The tumour must be located in a place that can be subjected to light For example, David

Dolphin and his collaborators developed porphyrin PDT for the treatment of skin cancers, for

which an external light source is sufficient

1.4

Porphyrin is coordinated to (a) magnesium in chlorophyll, (b) iron in hemoglobin, and (c) cobalt

in vitamin B-12

1.5

Toxicology is the study of the ill effects (toxicity) of substances on living organisms Before

introducing a porphyrin into the body for PDT, it must be established that the porphyrin, by

itself, has little or no significant toxicity

1.6

Non-medical applications of light-absorbing porphyrins include their use in rewriteable CDs and

DVDs, in making inexpensive electrodes for fuel cells, and as catalysts to produce ammonia

from nitrogen and hydrogen or split water into hydrogen and oxygen

1.7

Chemotherapy is the use in medicine of substances that are selectively toxic to malignant cells or

to a disease-causing virus or bacterium As such, a vaccine would not be considered chemotherapy Vaccines expose the body to substances that cause the body to make “antibodies”

that fight particular disease-causing viruses or bacteria The vaccine is administered before exposure to the virus or bacterium, and does not directly attack the disease-causing agent itself

The use of garlic to treat gangrene, on the other hand, is an example of chemotherapy Garlic is a mild antiseptic, which kills bacteria-infecting tissue leading to gangrene

1.8

Garlic is not generally considered to be toxic to humans, as it is used in the preparation of many foods Its beneficial health effects are associated with it containing antiseptic (antiviral, antibiotic and antifungal) and antioxidant agents The best known adverse effect on humans is bad breath

Garlic is, however, very toxic to microorganisms—it is an antibacterial and antifungal substance

1.9

Yes, arsenic is generally considered to be toxic However, Sec 6.1 discusses how the toxicity of arsenic varies dramatically depending on the species containing the arsenic atoms For example, whereas elemental arsenic is toxic, the arsenic-containing species in lobster are not This is why

we can eat lobster with no ill effects

1.10

Chlorophyll is a porphyrin coordinated to magnesium present in all photosynthesizing plants It could be used as a photosensitizer

1.11

The structures of both vitamin B-12 and VisudyneTM are porphyrin-based Both molecules’

porphyrin-backbone make them excellent candidates for photodynamic therapies

Section 1.3: Where There’s Smoke, There’s Gavinone 1.12

Hydrogen and carbon are the elements of polycyclic aromatic hydrocarbons—hence, the last term in this name They are polycyclic because their molecules consist of two or more rings of carbon atoms fused together They are aromatic because they are exceptionally stable relative to model compounds This is due to the spreading out (delocalization) of the π electrons over the ring(s) of an aromatic molecule bonding

A natural product is a compound produced by a living organism

1.14 (a) The Fujimoto-Belleau reaction converts enol lactones to cyclic α-substituted α,β-unsaturated

ketones

(b) Buckminsterfullerene consists of C60 molecules with carbon atoms arranged at the vertices

of a soccer ball

(c) Grignard reagents are alkyl halo magnesium compounds used to alkylate ketones

(d) Lindlar catalysts are used to add H2 to alkynes to make the corresponding alkenes They are made by depositing palladium on calcium carbonate, then treating with various forms of

lead

(e) Curium is the radioactive “transuranic” metal with atomic number 96 Its symbol is Cm

(f) A Zeigler-Natta catalyst is used to make polyethylene and related polymers It is made by

treating titanium compounds with alkyl aluminum compounds

(g) A Schiff base has a C=N−C fragment, which acts as a base through the nitrogen atom Such

compounds arise as intermediates in metabolic processes, and in the active sites of enzymes

(h) Wilkinson’s catalyst is a rhodium compound used to add H2 to alkenes to make the

corresponding alkanes

(i) Wittig reagents have a carbon phosphorus double bond They are added to aldehydes to

make alkenes

(j) Meitnerium is the radioactive element with atomic number 109 Its symbol is Mt

1.15 (a) The Haber process combines hydrogen and nitrogen to make ammonia Ammonia is used to

make fertilizer It was discovered by Fritz Haber

(b) In the Bohr model, a hydrogen atom consists of an electron in a circular orbit about a

proton The angular momentum of the electron is a multiple of Planck’s constant divided by 2π It was discovered by Niels Bohr

(c) A conical flask widely used in chemistry labs to carry out reactions It was invented by

Emil Erlenmeyer

(d) The van der Waals equation is a relation between the pressure, temperature, and volume of a

gas that accounts for the non-zero size of the gas molecules and the attractive forces between them It was discovered by Johannes Diderik van der Waals

(e) Gibbs free energy, G = H − TS, combines enthalpy and entropy to give a quantity that must

decrease for any processes that actually happen It was discovered by Josiah Willard Gibbs

(f) Lewisite is a chlorinated organoarsenic compound, which was produced as a chemical

weapon that causes blisters and lung irritation It was discovered by Winford Lee Lewis

(g) A Lewis base has a lone pair of electrons that it can donate to an electron pair acceptor—a

Lewis acid It was discovered by Gilbert N Lewis

(h) Schrödinger’s equation determines the wave function that describes the state of an atom It

was discovered by Erwin Schrödinger

1.16

(a) Canadian physicist Harriet Brooks-Pitcher discovered the transmutation of elements (the

transformation of one element into another) and the radioactive gas radon

(b) Marie-Anne Pierette Paulze was the wife of Antoine Lavoisier, the famous French chemist

She assisted her husband through her accurate drawings of experimental setups, editing his writings, and translating earlier works on phlogiston theory into French for her husband to read Lavoisier disproved phlogiston theory

(c) Rosalind Franklin, an English multidisciplinary scientist, is best known for her X-ray

diffraction images of DNA These images were used by Watson and Crick to formulate the

double helical structure of DNA

(d) May Sybil Leslie was an English chemist who did important work on radioactive elements,

and on explosives

(e) German chemist Ida Eva Tacke Noddack discovered the element rhenium in collaboration

with her husband She also first proposed the notion of nuclear fission

(f) French physicist Marguerite Perey discovered the element francium

(g) Margaret Hilda Thatcher studied chemistry and later became Prime Minister of the United

Kingdom (1979‒1990)

(h) Angela Merkel obtained a Ph.D in quantum chemistry and became Chancellor of Germany

in 2005

(i) Maud Menten was a Canadian physician-scientist She made significant contribution to

enzyme kinetics, and her name is linked to the well-known Michaelis-Menten equation

(j) Dorothy Crowfoot Hodgkin was a British chemist who made important advances to the field

of X-ray crystallography She confirmed the structure of penicillin, and elucidated the structure of vitamin B-12 (a porphyrin based compound), and was awarded with the Nobel Prize in chemistry in 1964

(k) Jane Marcet was born in London, England She wrote popular science textbooks Her book

entitled Conversations on Chemistry was her most popular and famous work

1.17

1.18

There are many possible responses—some examples include the following: caffeine (alertness

vs cardiac arrest), water (hydration vs hyponatremia), warfarin (blood thinner vs bleed out), Botox (beauty vs paralysis), salt (tasty food vs dehydration), vitamin C (vital for enzymatic processes vs iron poisoning), fluoride (improved teeth vs accumulation) and iron (treat anemia

1.19

An organic compound consists of molecules made from carbon, hydrogen and oxygen atoms

There can be other atoms (for example, nitrogen in the case of Gavinone), and there may be no oxygen or even hydrogen atoms, as in the case of graphene, graphite, carbon nanotubes, and fullerenes

1.20

The term “organic” is commonly used to label food grown without the use of chemical fertilizer, pesticides, hormones, genetic alteration, and related technologies At a supermarket, one can buy

“organic” apples and carrots These foods contain water and salts, which are not considered organic by organic chemists

1.21

1 Acetylsalicylic acid, the common mild pain reliever, is a derivative of the natural product, salicin, obtained from willow bark

2 Morphine, obtained from poppies, is a powerful pain reliever

3 Cocaine, obtained from the coca plant, is also a pain reliever—still used for topical pain relief

4 Quinine, an anti-malaria agent, was isolated from the bark of cinchona trees

5 Menthol, isolated from mint leaves, is a topical pain reliever, which also relieves itching

1.22

The chemical structure of the synthetic drugs is identical to those extracted from plants It is the impurities associated with the synthetic procedure, in the case of synthetic drugs, and those associated with the biological source and the means of extraction, in the case of natural products, that are different

1.23

Synthetic sources might be cheaper if the natural product is rare On the other hand, natural products might be cheaper if the drug can be obtained directly from an easily grown plant Also, natural products require only separation chemistry, so they reduce the need for chemical

reagents

1.24

Mycotoxins are toxins produced by fungi such as poisonous mushrooms Penicillin is a mycotoxin that is toxic to bacteria, making it the original antibiotic It is a natural product and an organic compound

SUMMARY AND CONCEPTUAL QUESTIONS 1.25

Excess production of porphyrin is the cause of porphyria Porphyria sufferers and patients undergoing PDT treatment both have excess porphyrins in their tissue, making them sensitive to light for the same reason

1.26

Due to their sensitivity, porphyria sufferers would avoid sunlight like the vampires of legend

Other symptoms of porphyria include skin blisters, skin colour change, dark red urine, and mental disorders Skin blisters on the neck might be interpreted as bite marks Dark red urine might be thought to be associated with the drinking of blood Mental disorders are consistent with the aberrant behaviour attributed to vampires

1.27

Antimony and arsenic are in the same group in the periodic table—antimony just below arsenic

It is natural that arsenic, having similar properties, might substitute for antimony in its compounds Since arsenic has the larger natural abundance, it might be expected to constitute a significant impurity in antimony compounds

1.28

Infrared light excites bends and vibrations of molecular bonds Infrared spectra are used to determine the types of bonds present in a molecule

1.29

Gavinone has alkane, alkene, ether, and ester functional groups It would give absorption peaks

in the following ranges (in cm‒1): 2850‒2980 (from the alkane group—note that C‒C stretches not shown in Table 3.5 will also cause absorption peaks); 1640‒1670 and 3020‒3100 (from alkene groups); 1085‒1150 (from ether group); and 1000‒1300 and 1730‒1750 (from ester group)