Week 11 Application Exercises – Molecules and Drugs

Application Exercises 9 — 05/04/17


  1. a) C5H9N3


  1. c) The hydrogens and the amine functional group are making histamine a    water-soluble compound.


  1. a) C20H22N3
  2. b) The presence of cyclic functional groups and nitrogen elements are structural similarities between histamine and antihistamines.


drugs creating a physiological response in the body drugs inhibiting the growth of substances that cause infections




antibiotic (Keflex)



  1. a) Herbal supplement manufacturers could argue that natural remedies such as herbs are known and used for centuries and generations and it worths all the clinical tests.

b) As a matter of fact we did not know anything about Singapore’s legislation on drugs but after some researches we can say that drug abuse is very severely punished in Singapore, some drugs are subsidised by the government and traditional chinese medicine is regulated by law (form and dosages). “Regulatory requirements for Chinese medicines are the same GMP rules used for conventional pharmaceuticals. Control mechanisms for CPM requirements include marketing authorization requirements and licensing of manufacturers. Regulatory requirements for safety include traditional use without demonstrated harmful effects, toxic heavy metal content and microbial content testing, and absence of prohibited ingredients. Licensing of dealers and product approval are required for every CPM product imported, manufactured or assembled.There are currently no registration requirements for herbal medicines and none are included on a national essential drug list; however, a listing system has been established for CPM products. The post marketing surveillance system for all herbal medicines has included adverse effect monitoring since 1993. There are no restrictions on the sale of herbal medicines, as long as they comply with the national regulations.” National policy on traditional medicine and regulation of herbal medicines Report of World Health Organization, Geneva, May 2005

Week 10 Application Exercise

1) Acetone dissolves the polymer causing some of the gas of the foaming agent to escape. As a result, the polymer collapses on itself and becomes denser due to the removal of the gas.

2a) LDPE cannot be used as it does not meet the minimum strength required.

2b) The molecules of HDPE must be arranged in a particular way in order for it to produce the required strength. By using a thin liner of HDPE, it will allow sufficient flexibility for its application in surgical gloves.

3) When a piece of plastic bag is stretches, the plastic becomes thinner and narrower at the center. The molecules align parallel to each other, in the direction of the pull. This action is irreversible as it alters the three-dimensional structure of the molecule and further stretching will tear the plastic. On the other hand, when paper is stretched with the same amount of pulling force, it will tear instead. This is due to the cellulose molecules in paper being more rigidly held in place, thus the molecules are not free to become aligned and will break apart.



4a) The properties of polymer that would be desirable for use in the human body are (1) stability over time of intended use and (2) non-toxic. (3) wide range of physical and chemical properties to meet the needs of its function by varying the monomer units (4)  Responsiveness to physical stimuli like mechanical stress

4b) There are many types of contact lenses on the market and each consist of a different polymer. One of the earliest polymers used for rigid gas permeable lenses, Polymethyl methacrylate (PMMA), is structurally similar to Lucite and Plexiglas. Silicone-acrylate materials are now more commonly used under trade names such as Kolfocon. Newer rigid gas permeable (RGP) polymers contain fluorine-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). It’s important to find out more before buying a product and manufacturers’ websites are often good sources of information. Some properties that are desirable in contact lenses include being non-toxic, permeable to oxygen, comfortable to wear and inexpensive. The ability to conform to the shape of the eye and ease of cleaning or whether it’s disposable are also qualities that are desirable and need to be considered when manufacturing contact lenses.


4c) As mentioned above, PMMA and rigid non-gas permeable plastic are typically used to make hard contact lenses. Soft contact lenses, which were developed to replace hard contact lenses, are made of silicone, which is flexible and allows oxygen to reach the eye. Due to these properties, soft contact lenses tend to be more comfortable.

Week 9 Application Exercise

1a) Coal-fired plants produce sulfur dioxide which will lead to the formation of sulfate particles in the air. Sulfate particles in the air can absorb and scatter light, causing poor visibility in Mammoth Cove National Park



b) pH of rainfall in the park is 4.6.

2a) Hanging laundry to dry instead of using dryer will reduce the usage of electricity. Renewable energy sources can better accommodate to the reduced usage of electricity by households and will depend lesser on the burning of fossil fuels for energy. The decrease in dependency of burning fossil fuels for energy will reduce the amount of sulfur dioxides and nitrogen oxides being produced. Formation of acid rain will be reduced due to the low concentration of sulfur dioxide and nitrogen oxides present in the air.

b) Taking public transport, bike or walk can reduce the number of cars present on the road. The combustion of fuels in car will produce nitrogen oxides and by reducing the number of cars on the road, lesser amount of nitrogen oxides will be emitted into the air. This will then reduce the formation of acid rain.


c) Avoid running dishwashers and washing machines with small loads as they do not maximise the use of energy and will lead to the over-consumption of energy. Energy is required to allow the constant flow of water through the tap and electricity is being used to allow washing machines to function. By maximising the use of energy, lesser energy will be wasted and will reduce the consumption of energy. Dependency on burning fossil fuels for energy will be reduced and lesser amount of sulfur dioxides and nitrogen oxides will be produced. This will then lead to the reduction of the formation of acid rain.

d) The installation of additional insulation on hot water heaters and pipes will help to reduce the temperature within the household. As the temperature within the household is being lowered, people within the household will rely lesser on electrical appliances such as fans and aircons to cool their surroundings down. Energy consumption will be reduced and production of energy through burning of fossil fuels will be reduced too, resulting in lesser amount of sulfur dioxides and nitrogen oxides being formed. This will then lead to the reduce the formation of acid rain.

e) Supporting locally grown produce and locally produced food will lead to the reduction in reliance of imported food and products. Importation of food and products from other countries or regions require transportation such as ships and airplanes, which will lead to the production of nitrogen oxides. Reducing the consumption of imported food and products will lead to the reduce in the need of transportation for the imported food and products. This will reduce the production of nitrogen oxides and then the formation of acid rain.


3a) Acids: Hydrochloric acid = HCL, Nitric acid = HNO3, Sulfuric acid = H2SO4, Phosphoric acid = H3PO4, Acetic acid = CH3COOH

Bases: Sodium hydroxide = NaOH, Calcium carbonate = CaCO3, Magnesium hydroxide = Mg(OH)2, Ammonium hydroxide = NH4OH, Calcium hydroxide = Ca(OH)2

b) Acids can generate electric current, turn blue litmus paper red and taste sour. Bases can generate electric current, turn red litmus paper blue and taste bitter.


4) Acid deposition can originate both inside and outside of the Singapore’s border.

The presence of power and industrial plants in Singapore can contribute to acid deposition by producing Sulfur dioxide and Nitrogen oxides as waste products. The heavy reliance on transportations in Singapore can also lead to the increase in production of Nitrogen oxides, causing acid deposition.

There are also other factors that can be found outside of Singapore that can cause acid deposition within Singapore. One example would be the annual haze produced by Indonesia’s slash and burn method. The haze was blown into Singapore by the South-Western wind from Sumatra and contains many air pollutants that may result in acid deposition.

In conclusion, we believe that acid deposition can originate from both inside and outside of the Singapore’s border.


Week 7 Application Exercise

1)  Water purifying capsules. The capsules are able to deactivate bacteria, viruses and parasites to make the water safe to drink but it cannot remove impurities in the water.

Boiling of water. Boiling water can remove most bacteria and viruses but it cannot remove impurities in the water. It is the cheapest method out of the three but it is time consuming.

Life Straw. The straw is able to filter most impurities, parasites and bacteria but it does not remove viruses and salt. It is more expensive than water purifying capsules but it is able to purify a larger volume of water.

All these methods are only a small part of the method to purify municipal water supplies. Sedimentation, Filtration, Disinfection, Water Fluoridation, Coagulation and Flocculation are the steps required to purify municipal water supplies.


2) This is because a lot of energy is required for the machines to perform desalination. Thus it is very expensive and not sustainable for the environment.


3a) The likely major source of the lead in the drinking water could be from the lead water pipe as it may corrode over time which will cause the water to be contaminated with lead.

3b) Yes. This is because some of the chemicals may not be properly disposed of and thus the chemicals may cause the lead water pipe to corrode thus contaminating the water supply.


4) Fat is non polar and water is polar. Polar compounds dissolve in polar solvents and non polar compounds dissolve in non polar solvents, hence only the water-soluble vitamins would be expected to be polar molecules.


Week 6 Application Exercise

  1. Due to human activities, a lot of energy is produced at the Earth’s surface constituting, with the reflected energy from the sun, the radiated energy of the Earth. Part of this energy gets trapped in the atmosphere by the greenhouse effect gases. This molecules, enriched in energy, are spinning faster which implies a raise of temperature.

2. Due to global warming, climate change is more extreme such that hot days get hotter and cold days get colder. Colder winter is a sign of fluctuating temperatures due to global warming increasing the need for concern. Therefore the statement is incorrect.

3. Microwave radiation has lower frequency than infrared radiation. Since energy of photons, E = hf (h being the planck constant and f the vibrating frequency), the energy of microwave radiation photons is too lowe to trigger rotation of water molecules.

Unsuccessful because it caused too much heat and became microwave ovens. Not suitable as a radar device but suitable as a cooking oven.


4. In the short run, air quality causes health issues and affects productivity.

In the long run, we can slow down ozone depletion but not stop it as the chain reaction causes chlorine to be constantly produced. As a result, more UV-vis radiation will penetrate the atmosphere, causing skin cancer and more energy will be reflected. Aquatic life species would be affected by UV rays and there is a possibility of extinction which will lead to imbalance of our ecosystem.


Week 5 Application Exercises


a)Exothermic. The burning of charcoal briquette releases heat during the process.
b) Endothermic – Water absorb the heat energy to evaporate.
c) Endothermic – Ice absorb the heat energy require to melt.





Ans: A good explosion would have a very negative enthalpy, which means that the  bond strengths in reactants must be higher than products as you can see from the equation above.



Heat is a form of energy transferred from one body to another, from a region of higher temperature to a region of lower temperature.

Temperature is not energy. It is a measure of the degree of hotness or coldness which is measured by different kinds of thermometer.

Q = mcΔT

Q = heat content in Joules

m = mass

c = specific heat, J/g °C

T = temperature

ΔT = change in temperature

Two different substances may have the same temperature but contains different amount of heat as the amount of heat depends on other factors such as mass and specific heat. Hence when a drop of hot water drops on you, you do not feel as pain as compared to a cup of hot water dropping on you as the cup of hot water contains higher mass which result in more heat being transferred to you.




a) The knocking characteristics of this gasoline is 98% isooctane and 2% heptane.

b) The octane number of the gasoline does not tell us whether or not it contains oxygenates. But,we do know that fuel with oxygenates have higher octane ratings, with common oxygenated fuel additives having octane ratings of over 100.



Week 4 – Protecting the Ozone Layer

Today we learnt about some of the advantages and disadvantages of using the term ozone screen as opposed to the term ozone layer to describe ozone in the stratosphere. The term ozone screen will give the misconception that it reflects the UV rays instead of absorbing it. It also gives people an impression that we are totally being screened from the UV rays which is not true.

We also learnt about some of the reasons that the solutions to ozone depletion proposed in the Sydney Harris cartoon will not work. This is because ozone is destroyed and produced at apporoximately the same rate, hence it is difficult to replenish the ozone layer as the rate of it being destroyed will increase.