AE9 (5/4/17)

1.

a. C5H9N3

b. The -NH2 at the extreme left end.

c. The amine group will contribute the most to the polarity of the molecule. This is the part that will interact the most with polar solvents such as water!

 

2.

a. C16N3H21

b. Both compounds have nitrogen-containing rings but they are of vastly different sizes which affects their properties.

 

3.

Antibiotics- Keflex, Penicillin

Other drugs-  Aspirin, Morphine, Estrogen, Amphetamine

 

4.

a. Bioactive ingredients found in herbal or alternative medicines are increasingly being clinically tested and documented to prove their effectiveness. Manufacturers are also seeking to improve quality control by having a scientific appraisal process, standardised production technology and as well as stringent quality control procedures. Research grants have been offered for formal medical studies conducted by medical researchers on the combined usage of herbal supplements and commonly used drugs such as aspirin, and level 1 clinical trial results have shown that combination usage of the medicines have no adverse effect.

b. Under Singapore’s Health Products Act and the Medicines Act, it is mandatory for all domestic manufacturers and assemblers of both therapeutic and traditional chinese medicine to comply with Good Manufacturing Practice (GMP) laid out by the Health Science Authority (HSA). All overseas manufactures are expected to comply with the local GMP standards as well. The GMP ensures that the production process of the medicinal products are consistent with the quality standards that is appropriate for their intended use. Singapore also adopts a post-market surveillance system consistent of two distinct components. First, regular samples and tests of products found in the market are conducted. Second, a local network of healthcare professional and global regulatory partners help to monitor and pick up advanced signs of any problematic health products that are causing adverse reactions. This two pronged approach helps Singapore to stay ahead and issue early recalls of harmful alternative medicine products.

 

AE 7 (22/03/17)

  1. Acetone will dissolve the polymer and the gas escapes from the foaming agent. Then, the polymer becomes smaller and denser when the gas escapes.
  2. LDPE cannot be used in the circumstance as it is not strong enough to withstand the potential pressures it would be subjected to. HDPE on the other hand is a much stronger polymer because of the way the layers of monomers are arranged. Using a thin layer of HDPE overcomes the its rigidity allows the gloves to be tough as well as flexible.
  3. No it does not. This occurs in plastic because the intermolecular bonds between the layers of plastic are weak enough to cause them to slide over one another. This ability is not facilitated by the rigid intermolecular bonds in paper (as it is not a pure polymer) Hence the paper does not exibit this property of stretching under pressure.
  4. First, it has to be non-toxic so that it does not adversely affect the patient. Next, it cannot be soluble as the human body contains water, fats and other solutions that could compromise the structural integrity of the implant. Also, it has to be stable once implanted into the body. Lastly, it should not be too expensive so that it can be available to the majority of patients. Contact lenses are made from PMMA, an early polymer developed specifically for this purpose. RGP and HEMA are also used in newer designs. Contact lenses should be non-toxic, clear, permeable to oxygen and comfortable to wear. Hard contact lenses are made from PMMA and are made to be more lasting. Soft contact lenses are based on silicon polymers which tend to be more comfortable and more permeable to oxygen.

AE 5 (22nd Feb)

  1. Boiling the water should kill off most bacteria and pathogens. Conversely, we can use iodine tablets to make the water safe for consumption. Boiling requires time and fuel  but is a rather inexpensive method of purifying water. On the other hand, iodine tablets are more expensive but are more convenient. Boiling is similar to the industrial distillation process, as it is the key process in this form of water purification.

 

2. Firstly, it is an energy intensive process which requires many resources. Secondly, it needs to be located near the sea in order to maximise transport efficiency which may not always be a viable option. These limitation are often overcome by using other water purification techniques.

 

3a. Corrosion of lead pipes or solder in drinking fountains or water storage tanks.

3b. No. There are separate pipes for drinking water and waste water. Furthermore, waste products from research activities should be specially handled and safely disposed of.

 

4. Water-soluble vitamins should be polar compounds while fat-soluble vitamins should be non polar. It is important to note that only polar solutes can dissolve in polar solvents such as water. Similarly, only non polar compounds can dissolve in non polar solvents such as fat. Therefore we can come to such a conclusion.

Application exercise 4: unit 5 (15/02/17)

  1. From the example, we can see that the amount of energy emitted form the surface is more than the energy striking the Earth’s surface. However, the Earth does not cool rapidly because the Earth’s surface absorbs a great amount of energy from the atmosphere.
  2. The understanding of the term “global warming” is wrong. Based on the statement, it assumed that global warming is only about the warming of atmosphere and snowing would mean that global warming is not much of a threat. However, global warming also causes heavier precipitation events such as heavier snow fall or unnatural events like snowing in the middle of summer.
  3. The design was unsuccessful because the absorption of microwave radiation by atmospheric water hinders with the detection of intended items.
  4. In the short term, air quality is the most serious problem because it has direct adverse impact to our health and it definitely has faster effects as compared to the other 2. In the long run, however, global warming is the most serious problem because global warming carries massive implications for a lot of processes. The detrimental effects of global warming trickle down to other aspects which affects our air quality and our way of life. Global warming will also increase the incidents of extreme weather events such as higher number of typhoons and hurricanes. (Hurricane Katrina :((((( )

Application exercise 3: unit 4 (08/02/17)

  1. a) Exothermic, heat is given off because it burns. b) endothermic, gains heat from body heat to evaporate c) endothermic, gains heat from surrounding.
  2. Good explosion is a rapid high energy reaction (very exothermic). For this condition to arise, the bond energies of the products have to be larger than those of the reactants. This will lead to a large negative net energy which shows an exothermic reaction.
  3. Heat is a consequence of motion at the molecular level while temperature is a measure of the average speed of that motion. An everyday example would be the usage of a metal spoon in a hot soup. The heat of the soup gets transferred to the spoon. There’s a difference in temperature between the bowl of the spoon and the handle of the spoon so heat travels from the bowl to the handle. The higher the heat energy, the faster the transfer.
  4. a) An octane number of 98 means a knocking characteristics of 98% of issoctane and 2% heptane. b)The octane rating shows us nothing about whether the fuel contains oxygenates.