Q1) In allergy sufferers, histamine causes runny noses, red eyes, and other symptoms. Here is its structural formula.





a. Give the chemical formula for this compound.

Answer: C5H9N3


b.Circle the amine functional groups in histamine.



c. Which part (or parts) of the molecule make the compound water-soluble?

Answer: The amine parts, as they form hydrogen bonds with water.


Q2) Antihistamines are widely used for 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.

Answer: 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?


When histamine and antihistamine are both present at the same time, antihistamine cancels the effects of histamine. This is because once antihistamine binds to the receptor site, it blocks the effects of histamine as histamine is unable to bind to the receptor site. No chemical messengers would be produced by histamine.


Q3) Consider this statement. “Drugs can be broadly classed into two groups: those that produce a physiological response in the body and those that inhibit the growth of substances that cause infections.” Into which class does each of these drugs fall into?

A) aspirin  B) morphine  C)(Keflex) antibiotic  D) estrogen  E) amphetamine  F) penicillin


Produce a physiological response in the body: A, B, D, E

Inhibit the growth of substances that cause infections: C, F


Q4) 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 manufacturers that address these issues?

Answer: We think that the product label should be prominently and conspicuously displayed on the product at the point of sale.  The name of the product, the recommended dosage, the batch reference and relevant precautionary statements should be displayed on the final product or package. In addition, leaflets or inserts should be used when the product itself is unable to contain all the information.

A) Do you know anything about Singapore’s legislation on the topic?

Answer: In Singapore, health supplements can be imported and sold without a license from Health Science Authority (HSA). The HSA provides guidelines, which should be followed.

According to HSA, there are several acts in Singapore’s legislation that cover health supplements:
A. Medicines Act (Chapter 176) & its Subsidiary Legislation especially:
i. Medicines (Prohibition of Sale & Supply) Order;
ii. Medicines (Traditional Medicines, Homoeopathic Medicines and Other
Substances) (Exemption) Order;
iii. Medicines (Non-Medicinal Products)(Consolidation) Order;
iv. Medicines (Labelling) Regulations;
v. Medicines (Medical Advertisements) Regulations;
vi. Medicines (Licensing, Standard Provisions & Fees) Regulations

B. Medicines (Advertisement & Sale) Act (Chapter 177)

C. Sale of Drugs Act (Chapter 282) & its Regulations especially:
i. Sale of Drugs (Prohibited Substances) Regulations;
ii. Sale of Drugs (Prohibited Drugs) (Consolidation) Regulations;
iii. Sale of Drugs (Rhodamine B) Regulations 1993

D. The Poisons Act (Chapter 234) & The Poisons Rules



  1. Health Supplements Guidelines [PDF]. (2015, February). http://www.hsa.gov.sg/content/dam/hsa/hprg/complementary_health_products/overview_framework_policies/health_supplements/hsguidelines.pdf

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. This solid still consists of Styrofoam, but now it is solid and much denser. Explain. (Hint: Remember that Styrofoam is made with foaming agents)


Acetone dissolves the polymer (Styrofoam), allowing the foaming agent to escape. Once the acetone has evaporated, the polymer remains and is now solid and more dense than before as it has collapsed due to the lack of foaming agent.


Q2) Consider Spectra, Allied-Signal Corporation’s HDPE fibre, 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 very 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.


LDPE does not have the required strength to resist being accidentally cut during surgery.


B) Offer a molecular-level reason for why linear HDPE is successful in this application.


As the arrangement of molecules affects the material’s flexibility, the arrangement of molecules in a linear fashion offers the material sufficient flexibility.


Q4) When you try to stretch a 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.


When the plastic bag is stretched, it necks and narrows down. Molecules become aligned parallel to each other and in the direction of the pull. When stretching paper in the same way, however, it does not stretch but breaks instead. This is due to the molecules in the cellulose in paper being arranged in a more rigid way that does not permit the molecules to be re-aligned like in the case of the plastic bag.


Q5) Some polymers are biocompatible and now used to repair human body parts.

A) List 4 properties that would be desirable for polymers used within the human body.


The materials should be non-toxic, should not degrade over time, easy to transplant into the body, and does not react with body tissues and fluids.


B) Other polymers may be used outside the body, but in close contact with it. For example, a surgeon is not needed to use contact lenses- they can be removed, stored, and cleaned 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.


Polymethyl methacrylate (PMMA), polyacrylamide, and rigid gas permeable (RGP) polymers. Properties desirable in these materials include: does not react with substances on the eye surface, permeable to oxygen so as to allow oxygen to reach the eyeball, easy to manufacture, comfortable to wear, and easily deformable so as conform to the shape of the eyeball. Ease of cleaning is also important for reusable contact lenses.


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 contact lenses?


“Hard” lenses are usually made of PMMA, which was more rigid and non gas-permeable. “Soft” lenses are made of silicone, PMMA and fluoruopolymers, which is more flexible and allowed oxygen to permeate through it to reach the eyeball. The soft lenses may be more comfortable due to these properties.



  1. Polymers in everyday things- contact lenses [PDF]. (n.d.). RSC. http://www.rsc.org/Education/Teachers/Resources/Inspirational/resources/3.1.1.pdf

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 power plants generate sulphuric acid which reduces visibility especially in the summer months when there is more sunlight. This is because the sulphuric acid forms small droplets which in turn form aerosols that reflect sunlight rather than absorb it, reducing visibility.

B) The NPCA reported that “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 the rainfall in the park.


Normal rain is slightly acidic, about pH 5.3. This means that the pH of the rain in Mammoth Cave is 4.3. This is because a decrease of 1 on the pH scale, which is a logarithmic scale, corresponds to two substances differing in H+ concentration by 10 times.


Q2) Here are some 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.

Drying laundry via hanging eliminates the need to generate additional energy in order to operate clothes dryers. This means less energy will be needed to be generated via coal, decreasing the SOx emissions from coal-fired power plants. SOx emissions contribute to acid rain, so decreasing their emissions would regulate the pH of rain.

B) Walk, bike, or take public transportation to work.

This reduces the amount of NOx generated by vehicles as compared to everyone taking public transport. Since NOx emissions also contribute to acid rain, reducing NOx emissions would also help in regulating the pH of rain.

C) Avoid running dishwashers and washing machines with small loads.

Not maximising the capacity of the machine results in an inefficient use of energy, which means there is wastage of energy generated via coal. Since generating energy via coal results in SOx emissions into the atmosphere, it is important to make sure any energy is used efficiently.

D) Add additional insulation on hot water heaters and pipes.

Adding additional insulation prevents heat from the water from escaping into the environment easily. This reduces the need to reheat water that has lost heat due to lack of insulation. Extra energy is thus not used to reheat the water, reducing the need for energy via coal-fired power plants that emit SOx into the atmosphere.

E) Buy locally grown produce and locally produced food.

This reduces the amount of energy needed to transport food from farm to table. Imported food needs to travel a longer distance to reach us and the extra NOx and SOx generated to provide energy to transport the food over longer distances can contribute to acid rain.



A) Give names and chemical formulas for 5 acids and 5 bases.



  1. H2SO4 Sulphuric acid
  2. HCl Hydrochloric acid
  3. H3PO4 Phosphoric acid
  4. HNO3 Nitric acid
  5. H2CO3 Carbonic acid


  1. NaOH Sodium hydroxide
  2. LiOH Lithium hydroxide
  3. KOH Potassium hydroxide
  4. Ca(OH)2 Calcium hydroxide
  5. Ba(OH)2 Barium hydroxide

B) Name three observable properties generally associated with acids and bases.

  • Acids: have a sour taste, turns blue litmus paper red, turns phenolphthalein colorless
  • Bases: have a bitter taste, turns red litmus paper blue, turns phenolphthalein pink


Q4) The concerns of acid rain vary across the globe. Many countries in North America and Europe have websites dealing with acid rain. Either search to locate one (“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 Singapore’s borders?


Some issues in Singapore could include health hazards such as haze, and infrastructure issues when acid rain comes into contact with buildings, where money could be involved to repair the infrastructure. Also, the biodiversity of animals could be affected due to acid rain, as most aquatic animals cannot survive below pH 5. Singapore has several fish farms, and a decrease in pH could affect the fish in the water.

Our group thinks that acid deposition originates from both inside and outside Singapore. For example, in the case of haze, the acid deposition originated from outside Singapore. However, acid deposition originating inside Singapore could come from sources such as Jurong Island, where there are refineries, and car exhausts from our transport systems.



  1. Gunasingham, A. (2009, September 14). Native species in Singapore may be wiped out by acid rain. Retrieved March 16, 2017, from http://wildsingaporenews.blogspot.sg/2009/09/native-species-in-singapore-may-be.html#.WMjlNu5EmM8


Q1) How can your purify water when 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.


One method of distillation is boiling the water (using solid fuel or starting a fire from wood) and collecting the condensed steam on a sheet. Another method involves the use of a small water purification device that can be purchased from stores. Both methods involve the use of equipment, especially in the second method. The first method may be easier to use as more of the items can be found from the surroundings (e.g. wood) but it is slower than the second method. The second method involves the use of special equipment that perhaps only experienced hikers would carry, although it may be faster to obtain purified water than the first method. None of these methods are similar to the ones used to purify municipal water supplies as the purification process at the treatment plants involve the adding of various chemicals in various stages and involves equipment ans substances which the average person would not have access to.


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


Desalination techniques come at a relatively high cost and thus will not be used on as large a scale as cheaper methods as long as these cheap methods are available and able to meet demand for potable water. Also, the quantity of potable water produced from desalination is little. For example, Tampa Bay Water’s facility is the largest seawater desalination plant in North America but it can only produce 25 mgd of water at full capacity, which only satisfies about 10% of the region’s needs.


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 the NEA.

A) What is the the likely major source of the lead in the drinking water?


Likely sources include: the pipes (if plumbing is not done properly), soldering, and corrosion of the pipes in which the pipes are old and cracked.

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


Yes, if improper disposal of chemicals is being carried out, with these chemicals being dumped into a place where it is able to leak into the drinking water.


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


We would expect the water-soluble vitamins to be polar and the fat-soluble vitamins to be non-polar. This is because like dissolves like, and since water is a polar substance it can dissolve the water -soluble vitamins which are also polar. Since fat is a non-polar substance it should dissolve the fat-soluble vitamins which are also non-polar.



  1. Water supply. (n.d.). Retrieved February 22, 2017, from http://www.tampabaywater.org/tampa-bay-seawater-desalination-plant.aspx

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?


Even though the amount of energy emitted from the Earth’s surface is more than double the amount received from the Sun, the Earth does not cool rapidly because the Earth’s surface absorbs a large amount of energy from the atmosphere.


Q2) Decide and explain where the statement is correct or incorrect.


The statement is incorrect for a number of reasons. First, the two people are assuming that just because their winter is colder than usual, global warming, which is a global phenomenon, must not be as severe as previously thought. They have confused weather, which refers to day-to-day changes, with climate, which refers to long-term patterns. In this case, the people assume the weather they are experiencing at the moment can be generalised to describe global climate patterns. Second, they do not realise that the heavy snowfall they are experiencing could in fact be a result of climate change brought about by global warming, as climate change results in more extreme weather.


Q3) One of the first radar devices developed during World War 2 used microwave radiation of a specific wave range that triggers the rotation of water molecules. Why was the design not successful?


It was because the absorption of microwave radiation by H2O 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)?


Short run: Though the burning of fossil fuels contributes to global warming and decreased air quality, air quality has a direct impact on our everyday lives and can affect human health over a much shorter time frame than processes such as global warming. It is thus more of a concern in the short run.

Long run: Though ozone depletion and global warming are caused by human activities, there are already many regulations targeted at reducing the amount of chlorine, which depletes ozone, in the air. However humans as a whole are still burning fossil fuels which generate CO2 which contributes to global warming. The effects of global warming, which includes climate change, are also visible through climate patterns which can only be observed over longer periods of time.

Q1) From personal experience, state whether these processes are endothermic or exothermic. Give a reason for each: A) a charcoal briquette burns, B) water evaporates from your skin, C) ice melts.


A) It is exothermic. Burning is combustion which is an exothermic reaction.

B) It is endothermic. In order to change from liquid to gaseous state, water takes in heat from the surroundings in order to evaporate.

C) It is endothermic. In order to change from the solid state to the liquid state, ice needs to take in heat from the surroundings.


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 in the reactants should be higher than the bond energies in the products. This results in an exothermic reaction as heat is released during the reaction.

For example: CH4 + 2O2 -> CO2 + 2H2O

Bond breaking:

4 (C-H) + 2 (O=O)

4(416) + 2(498) = 2660

Bond forming:

2 (C=O*) + 2 (2 H-O bonds)

2(803) + 4(467 )= 3474

3474 – 2660 = -814


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


Heat is form of energy which flows from a hotter body to a colder body. This can be seen when you hold a hot cup of coffee and your hand becomes warm. This is due to heat flowing from the hotter body (the cup) to a colder body (your hand). Temperature determines the direction of heat flow. In this case, since the cup has a higher temperature than your hand, the heat will flow from the hot cup to your hand.


Q4) A premium gasoline available at most stations has an octane rating of 98. What does this tell us about A) the knocking characteristics of this gasoline and B) whether the fuel contains oxygenates?


A) The fuel has a knocking characteristic of 98% isooctane and 2% heptane

B) The fuel does not contain oxygenates as the octane rating of the fuel (98) is too low for the fuel to contain oxygenates.