Application Exercise 9

1. In allergy sufferers, histamine causes runny nose, red eyes, and other symptoms. Here is its structural formula.

a. Give the chemical formula for this compound: C5H9N3

b. Circle the amine functional groups in histamine:

c. Which part (or parts) of the molecule make the compound water-soluble: Amine group and -NH group form hydrogen bonds makes the molecule water soluble.

2. Antihistamines are widely used drugs for treating symptoms of allergies caused by reactions to histamine compounds. This class of drug competes with histamine, occupying receptor sites on cells normally occupied by histamine. Here is the structure for a particular antihistamine.

a. Give the chemical formula for this compound: C16H21N3

b. What similarities do you see between this structure and that of histamine (shown in the previous question 1) that would allow the antihistamine to compete with histamine?

Both molecules have amine functional group. However, the amine functional group on antihistamine is less reactive as it is more hindered.

3. Consider this statement. “Drugs can be broadly classed into two groups: those that produce a physiological response and those that inhibit the growth of substances that cause infections.” Into which class does each of these drugs fall?

Physiological response: morphine, estrogen, amphetamine

Inhibit infections: aspirin, antibiotic, penicillin

4. Herbal or alternative medicines are not regulated in the same way as prescription or OTC medicines. In particular, the issues of concern are identification and quantification of the active ingredient, quality control in manufacture, and side effects when the herbal remedy is used in conjunction with another alternative or prescription medicine.

a. What do you think is the evidence from herbal supplement manufacturer that address these issues?

Evidence can be gathered from the new and unknown side effects from the herbal medicines. These side effects may not be identified because clinical trial regulations may not be as strict prior to the release of the herbal medicine.

b. Do you know anything about Singapore’s legislation on the topic?

Singapore requires clinical trials to be done for all medicines, however, the stringency of each class of medicine may differ. Therefore, legislation for herbal medicine may not be as strict as that of a brand-name drug. Singapore do require manufacturers to ensure that all herbal medicine do not contain any substance controlled under the Poison Act; the heavy metal content do not exceed the stated amount; the labels and packaging materials of the herbal medicine  do not stipulate any of the 19 diseases/conditions specified in the Schedule of the Medicines Act.

Application Exercise 7

Q1. When Styrofoam packing peanuts are immersed in acetone (the primary component in some nail- polish removers), they dissolve. If the acetone is allowed to evaporate, a solid remains.The solid still consists of Styrofoam, but now it is solid and much denser. Explain. Hint: Remember that Styrofoam is made with foaming agent.

Dissolving the polymer in acetone allows the gas of the foaming agent to escape. After the removal of gas, the polymer collapses on itself and becomes denser.

Q2. Consider Spectra, Allied-Signal Corporation’s HDPE fiber, used as liners for surgical gloves. Although the Spectra liner has a very high resistance to being cut, the polymer allows a surgeon to maintain a delicate sense of touch. The interesting thing is that Spectra is linear HDPE, which is usually associated with being rigid and not very flexible.

a. Suggest a reason why branched LDPE cannot be used in this application.

It does not have the required strength.

b. Offer a molecular level reason for why linear HDPE is successful in this application.

The molecules of HDPE must line up in a way that produces the required strength. Using a thin liner of HDPE allows sufficient flexibility.

Q3. When you try to stretch a piece of plastic bag, the length of the piece of plastic being pulled increases dramatically and the thickness decreases. Does the same thing happen when you pull on a piece of paper? Why or why not? Explain on a molecular level.

Stretching of the plastic bag cause the plastic strip to narrow and “neck down”. The alignment of molecules cause them to be parallel to each other and in the direction of the pull. This alteration of the 3D structure is irreversible, and would cause the plastic to break if the pulling continues. 

When the same pulling force is applied to a piece of paper, the paper will tear instead.  This is because the cellulose molecules in paper are held far more rigidly in place and hence unable to be moved to align.

Q4. A Teflon ear bone, fallopian tube, or heart valve? A Gore-Tex implant for the face or to repair a hernia? Some polymers are biocompatible and now used to replace or repair body parts.

a. List four properties that would be desirable for polymers used within the human body 

1. stable over time of intended use

2. non-toxic

3. low cost

4. lack of solubility and reactivity in body fluids

b. Other polymers may be used outside your body, but in close contact with it. For example, no surgeon is needed for you to use your contact lenses—you insert, remove, clean, and store them yourself. From which polymers are contact lenses made? What properties are desirable in these materials? Either a call to an optometrist or a search on the Web may provide some answers.

There are several different types of contact lenses on the market which uses different types of polymer. Polymethyl methacrylate (PMMA) is one of the earliest polymers used for rigid gas permeable lenses. Currently, Kolfocon is the commonly used trade name for silicone-acrylate materials. Newer rigid gas permeable (RGP) polymers contain fluorine: fluoro-silicone-acrylate polymers and fluoro-silicones. Polymacon (38% water) is typical of the polymers used for soft lenses and is a polymer of 2-hydroxyethyl methacrylate (HEMA). Other methacrylates include hioxifilcon(48% water) and methafilcon (55% water) or even lidofilcon (70% water). These materials have desirable properties such as being non-toxic, permeable to oxygen, comfortable to wear, and inexpensive. Other important quality include the ability to conform to the eye shape and easily cleaned.

c. What is the difference in the material used in “hard” and “soft” contact lenses? How do the differences in properties affect the ease of wearing of contact lenses?

Hard contact lenses are typically made of PMMA, a rigid non-gas permeable plastic. The soft contact lenses that replaced them are made of silicone, which is flexible and allows oxygen to reach the eye. Because of these properties, the soft lenses tend to be more comfortable

Application Exercise 6

Q1. Mammoth Cave National Park in Kentucky is in close proximity to the coal-fired electric utility plants in the Ohio Valley. Noting this, the National Parks Conservation Association (NPCA) reported that this national park had the poorest visibility of any in the country.

a. What is the connection between coal-fired plants and poor visibility?

Coal-fired plants release sulphur dioxide, creating sulphate particles that are responsible for 60 to 85% of the poor visibility in eastern parks.

b. The NPCA reported “the average rainfall in Mammoth Cave National Park is 10 times more acidic than natural.” From this information and that in your text, estimate the pH of rainfall in the park.

Normal rain has a pH range of 5–6, so if the rainfall in this park is 10 times more acidic, the pH range must be 4–5 since pH is a log scale based on 10, a pH change of 1 unit represents a power of 10 change in [H+].

Q2. Here are examples of what an individual might do to reduce acid rain. For each, explain the connection to producing acid rain.

a. Hang your laundry to dry it.

Hanging laundry to dry requires less energy than using a electric dryer. Cutting down on energy use cuts down on the need for power companies to produce electricity by burning coal, hence decrease the amount of SO2 emission thus decrease the production of acid rain.

b. Walk, bike, or take public transportation to work.

All of these transportation method reduces the amount of gasoline (or other energy source) used, cutting down on NO emissions and thus contributing less to the acidity of the rain.

c. Avoid running dishwashers and washing machines with small loads.

 Avoid running dishwashers and washing machines with small loads will reduce cutting down on energy use cuts down on the need for power companies to produce electricity by burning coal, hence decrease the amount of SO2 emission thus decrease the production of acid rain.

d. Add additional insulation on hot water heaters and pipes.

Reduce heat loss of the hot  water heater and pipes hence reducing extra energy used to keep water hot. This will decrease the need to produce electricity by burning coal, hence decrease the amount of SO2 emission thus decrease the production of acid rain.

e. Buy locally grown produce and locally produced food.

Buying locally grown produce can decrease the sale of industrial food production which is mostly dependent on fossil fuels when refined and burned can emit SO2 and NO which is the main cause of acid rain.


a. Give names and chemical formulas for five acids and five bases.


Sulphuric acid (H2SO4)

Nitric acid  (HNO3)

Chromic acid (H2CrO4)

Boric acid (H3BO3)

Acetic acid (CH3COOH)


Lithium hydroxide (LiOH)

Sodium hydroxide (NaOH)

Potassium hydroxide (KOH)

Calcium hydroxide (Ca(OH)2)

Barium hydroxide (Ba(OH)2)

b. Name three observable properties generally associated with acids and bases.

Acids are sour while Bases are bitter.

Acid turn blue litmus paper red while Bases turn red litmus paper blue.

Both acid and bases conduct electricity.

Q4. The concern of acid rain vary across the globe. Many countries in North America and Europe have websites dealing with acid rain. Either search to locate (“Canada, acid rain”) or use these links to websites in Canada, the UK, or Europe. What are the issues in Singapore? Does the acid deposition originate outside or inside the Singapore’s borders?

Issues in Singapore:

Haze- Forest burning from neighbouring country

Increase in mean temperature

Rising sea level

The acid deposition originate both inside and outside of Singapore’s border. However, the extent of acid deposition is higher outside of  Singapore’s border.

Acid deposition originate from the inside of Singapore due to the factories that emits SO2 and NO gases as they burn coals for energy but this is a small amount because the government set regulation to control the amount of harmful gases emitted.

Acid deposition originate from the outside of Singapore’s border such as forest burning in Indonesia which releases harmful gases that can lead to acid rain. This is a more serious problem because the authorities in the country do not regulate the amount of harmful gases emitted hence the acid deposition is more serious outside Singapore.

Application Exercise 5

Q1. How can you purify your water when you are hiking? Name two or three possibilities. Compare these methods in terms of cost and effectiveness. Are any of these methods similar to those used to purify municipal water supplies. Explain. 

Purify water by boiling, Use water purification tablet, Use small amount of household bleach.

Boiling kills many microorganisms that may make you sick, but requires time and will not remove chemical contamination. Boiling also requires time, fuel, and may release soot and CO to the environment.

Water purification tablet such as iodine tablet is easy and effective in twenty minutes, but it should not be used long-term. In addition, pregnant women and people with thyroid conditions should avoid purification with iodine. While iodine renders water bacteriologically safe, it doesn’t remove chemical contaminants. Many people dislike the taste of iodine-treated water.

Using a small amount of household bleach will kill some but not all microorganisms. Many people dislike the resulting taste.


Q2. Explain why desalination techniques, despite proven technological effectiveness, are not used more widely to produce potable drinking water.

The two most common desalination techniques are distillation and reverse osmosis. Both of these require large amount of energy to remove salts from seawater, and thus inherently are expensive. If a less expensive option is available, then the less expensive option is used.


Q3. Water quality in a chemical engineering building on campus was continuously monitored because testing indicated water from drinking fountains in the building had dissolved lead levels above those established by NEA.

a. What is the likely major source of the lead in the drinking water?

The likely source of lead is from solder in the pipe joints or from lead pipes themselves.

b. Do the research activities carried out in this chemistry building account for the elevated lead levels found in the drinking water? Explain.

Research activities should not contribute to lead in the drinking water, assuming that any lead compounds are disposed of using prescribed methods. Although many undergraduate chemistry experiments used to use lead, most now have been redesigned to avoid it and other toxic metal ions completely.


Q4. Some vitamins are water-soluble, whereas others are fat-soluble. Would you expect either or both to be polar compounds? Explain.

Fat-soluble is non-polar and water-soluble is polar compound. Fat-soluble contains long chain of non-polar hydrocarbons while water soluble compound contains polar chains.

Application Exercise 4

Q1. Understanding Earth’s energy balance is essential to understanding the issue of global warming. For example, the solar energy striking Earth’s surface averages 168 watts per square meter (W/m2), but the energy leaving Earth’s surface averages 390 W/m2.Why isn’t Earth cooling rapidly?

Answer: Earth does not cool rapidly because the atmosphere retains most of the emitted heat energy, even though the amount of energy emitted is more than double the amount of heat received. 


Q2. Decide and explain whether the statement is correct or incorrect. 

Answer: The statement is incorrect. The winter experienced in the cartoon should raise their concern about global warming because the amount of snow is not normal as there is too much snow. This shows erratic climate change which should be a concern as a result of global warming.


Q3. One of the first radar devices developed during World War II used microwave radiation of a specific wave range that triggers the rotation of water molecules. Why was the design not successful?

Answer: Absorption of microwave radiation by water molecules in the atmosphere interferes with the detection of intended objects.


Q4. Now that you have studied air quality (unit 1), stratospheric ozone depletion (unit 2), and global warming (unit 3), which do you believe poses the most serious problem for you in the short run (pick one and explain)? In the long run (pick one and explain)?

Answer: In the short run, air quality poses the most serious problem because it causes immediate harmful effects on human’s respiratory system.

In the long run, global warming poses the most serious problem because it leads to climate change and stratospheric ozone depletion which are irreversible, affecting the entire human population as well as ecosystem instead of a particular region.

Application Exercise 3

Q1. From personal experience, state whether these processes are endothermic or exothermic. Give a reason for each.

a. A charcoal briquette burns.

Exothermic. Heat is being released when the charcoal briquette burns.

b. Water evaporates from your skin.

Endothermic. Water absorbs heat for evaporation.

c. Ice melts.

 Endothermic. Ice absorbs heat to melt.

Q2. Chemical explosions are very exothermic reactions. Describe the relative bond strengths in the reactants and products that would make for a good explosion.

The bond energies of the products have to be larger than the bond energies of the reactants to result in an exothermic reaction, which would then make for a good explosion.

Q3. How might you explain the difference between temperature and heat to a friend? Use some practical, everyday examples. 

Heat is a form of energy and it flows from a warmer body to a colder body. Temperature is a measurement that indicates the direction of heat flow. For example, when a cup of hot water is poured into a cup of cold water, the heat will flow from the hot water to the cold water and the resulting temperature is a mixture of both.

Q4. A premium gasoline available at most stations has an octane rating of 98. What does that tell you about:

a. knocking characteristics of this gasoline?

Gasoline with an octane rating of 98 has the same knocking characteristics as a mixture composed of 98% isooctane and 2% n-heptane and is more resistant to knocking than other blends sold at stations.

b. whether the fuel contains oxygenates?

No, it does not tell us whether the fuel contains oxygenates.