Tag Archives: AE

CM8001 – Application Exercise 8 (05/04/2017)

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Q1

a)C5H9N3

c) Amine functional group will form hydrogen bomb. with water molecules to make it water soluble.

Q2)
a) C16H21N3
b) They have in common a substituted ethylamine moiety (-CH2-CH2-N-) as an integral part of their molecule

Q3) Drugs that give physiological response in the body
-aspirin
-esterogen
-morphine
-ampethamine

Drugs that inhibits the growth of substances that cause infection
-penicillin
-(keflex) antibiotic

Q4)
a) All drugs are regulated in the US by the FDA. Herbal/traditional/chinese medicines are treated like supplements than drugs. As such, they’re not placed under the same tight and strict regulations medicines and drugs have to go through. This is why such supplement/traditional medicines do not need to go through clinical trials.

b) Health supplements like those are not subjected to approvals prior to import and sale in Singapore.

CM8001 – Application Exercise 7 (23/03/2017)

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1) Styrofoam is almost 95% air (the foaming agent), and when dissolved in a solvent such as acetone, the reaction releases all the air that has been compressed in the styrofoam. What remains is only the styrene which makes it more solid and denser compared to its original form.

2a) Branched LDPE does not have a crystalline structure. It has a weaker intermolecular forces of attraction so the material is not as strong. Hence, it cannot have high resistance to being cut like HDPE.
2b) HDPE is linear giving a crystalline structure so that the attraction between molecules is stronger and has the necessary strength. At the same time, by using a thin layer as liners can reduce the rigidity so that it is more flexible yet the strength can be maintained which is important for surgical gloves.

3) When the piece of plastic is stretched, the strip narrows and neck down. The molecules become align parallel to each other and in the direction of the pull. This alteration of the three dimensional structure is not reversible, and if pulling continues, the plastic breaks.

When the same pulling force is applied to a piece of paper, the paper tear rather than stretching. The cellulose molecules in paper are hold far more rigid in place and are not free to aligned.

4a) They must not react with our bodily fluids, must be non-toxic to our bodies, have to be stable over time for the intended use and they would have to be easily implanted.
They would have to be non-toxic to the human body.

4b) Contact lenses are made up of either acrylamide, fluorosilicone acrylate or methyl methacrylate. Contact lenses that are made up of acrylamide are called soft lenses whilst contacts made from fluorosilicone acrylate or methyl methacrylate are called Rigid Gas Permeable (RGP) or Gas Permeable (GP) lenses. Soft lenses are desirable as the polyacrylamide lattice is polar hence highly hydrophilic. This is beneficial to those who frequently suffer with dry eyes that would make wearing contact lenses very uncomfortable. Flurosilicone acrylate was chosen as it has a high oxygen permeability and methyl methacrylate was chosen due to its ability to enhance optical quality and stability.

4c) The main difference is that soft contact lenses are made of silicone as compared to hard contact lenses which are made of PMMA, a non-gas permeable plastic. What this means is that the new property of the soft contact lenses allow oxygen to reach the human eye as compared to the hard contact lenses. the result is that soft contact lenses feel more comfortable for the human eye.

CM8001 – Application Exercise 6 (15/03/2017)

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1a) Burning coal produces some amount of SO2, which reacts with oxygen and water in the air to form sulfuric acid. Molecules of sulfuric acid in the air form tiny droplets (aerosols) that reflects sunlight, thus reducing visibility (much like haze).

1b) Since pH is a logarithmic scale, 10 times increase in acidity translates to 1 point decrease in pH. pH of rainwater is around 5.3 naturally, hence the pH of rainwater in the park is estimated to be around 4.3.

2a) Electricity is needed to run electric dryer and burning of coals will be required to generate electricity. This process emits gases like sulfur dioxide. Sulfur dioxide going into the atmosphere will react with water to form acid rain. Hang clothes to dry will not need electricity.

2b) Large amount of NOx is emitted from vehicles, hence, contributing to acid rain when it reacts with water. By taking public transport, walking and bike will reduce the amount of NOx emission.
2c) Electricity is needed to run the dishwashers and washing machines. By accumulating more dishes, it reduces the usage of the machines, hence, less electricity is used which in term reduces the amount of sulfur dioxide produced from coal-fired electric power plant.

2d) Heating up the water requires burning of fossil fuels. By adding additional insulation, it reduces the amount of heat loss, keeping the temperature slightly higher compared to uninsulated pipes. Hence, less energy is required to heat up the water since temperature can be maintained. Less sulfur dioxide produces from power plants will reduce acid rain.

2e) By buying home grown food, this reduces the need to import food from other countries. This reduces the distance for the food to be transported especially if it is from other countries. Hence, less pollutants like CO2, SO2 and NOx will be produced during transportation and they are sources for formation of acid rain.

3a) Give the names and chemical formulas for five acids and bases

Hydrochloric Acid, HCl
Sulfuric Acid, H2SO4
Ethanoic Acid, CH3COOH
Phosphoric Acid, H3PO4
Fluoroantimonic Acid, HSbF6

Sodium Hydroxide, NaOH
Ammoniun Hydroxide, NH4OH
Barium Hydroxide, Ba(OH)2
Aluminium Hydroxide, Al(OH)3
Iron II Hydroxide, Fe2(OH)2

3b) Name three observable properties generally associated with acids and bases
Acids generally have a sour taste whereas bases generally taste bitter.
When red litmus paper is dipped into a base it turns red and when a blue litmus paper is dipped into an acid it turns blue
Bases have a soapy feel to it whilst strong acids can burn our hands due to their corrosiveness.

4) The acid depositions can be originated from inside and outside singapore’s borders, but mainly inside.

Singapore does actually experience acid rain to a certain extent. The lower pH record in some location suggest that acidic ions released are contributed by SOx and NOx from coal-burning from heavy industries, in places like Jurong Island and western part.

The acid deposition is also came from ship that used fuel with a much lower sulfur content and emits a lot of SOx.

While outside Singapore’s border, action from our neighbors such as indonesia whose forest caught fire will lead to contributing acid deposition. Other than that, other asian nation which also grow into industrialization can also contribute to large number of SOx emission.

Hence, the acid deposition here originates from both inside and outside Singapore’s borders.

CM8001 – Application Exercise 5 (23/02/2017)

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  1. Water purification tablets: Commercially available tablets containing iodine or chloride-based chemicals used to disinfect water.
    Compared to boiling water, it may be less effective in killing bacteria, protozoa, or viruses, but it is less costly & less bulky to carry than boiling equipments.
    This method is similar to the chlorination process in water treatment, which uses chemicals (chlorine in particular) to kill disease-causing organismsBoiling: The most primitive yet effective way to treat water.
    Compared to water purification tablets, boiling is more effective in killing bacteria, protozoa, and viruses. However, the equipments required to boil water are more expensive & more bulky to carry around.

    Portable pump filter: Some commercially available filter uses ceramic filter as the cartridge to filter impurities in water. It can filter up to the micrometer. This filters most of the bacteria, making water safer to drink. It is portable and easy to carry during outdoor activities, hiking.
    However, it is less effective in filtering viruses since they are generally smaller in size. Also, depending on the types of filters, the price varies. It is still generally more expensive as compared to boiling and water purification tablets.
    Portable pump filter is analogous to the filtration method used in water treatment. It is only a scale down version since it is made portable.

  2. Although desalination techniques have their technological effectiveness, the energy required to use the techniques are so high that it’s too costly and expensive for a lot of countries, especially third world countries. The desalination plants itself are expensive to build as well.
    There are also environmental concerns as desalination plants take in salt water from the ocean and this is harmful to ocean life as the water travels straight from the ocean directly into the plant. There is also waste created during the process. When the salt is removed from the seawater, a waste called brine is produced. Water containing brine is denser and as a result will sink to the bottom of the ocean. Therefore, resulting in the lack of oxygen which will eventually kill marine-life.
    Besides environmental concerns concerning the ocean, desalination techniques also produces greenhouse gases.
  3.  a) The major source of the lead is from solder in pipe joint or directly from lead pipe.
    b)- Research activities should not contribute to lead in drinking water and disposed of using prescribed method or redesign the chemistry experiment to avoid using lead and any other toxic metal ions.
    – Using two plumbing system, one for the tap/drinking water service system and the other for sanitary or disposal system, so the two pipes doesn’t come in contact
  4. The water-soluble vitamins, vitamins B and C, are polar whilst the fat-soluble proteins are non-polar. Polar molecules will have the ability to form permanent dipole – permanent dipole interactions with water however non-polar molecules cannot as even if their are polar bonds within the molecule, the fact that the majority of the molecule being non-polar would make the molecule insoluble.

CM8001 – Application Exercise 4 (15/02/2017)

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Q1) Instead of directly reflecting back to space, most of the energy leaving the Earth’s surface can be trapped and retained by the greenhouse gases at the atmosphere (e.g. Methane, Ozone, Carbon dioxide, water vapour, Nitrous oxide). Hence, this maintains the Earth’s temperature and will not cool rapidly.

Q2) The statement is incorrect because the rise of temperature as the cause of global warming may be intensifying the effects of the jet stream’s position, which in the winter can cause extreme cold weather and caused extreme climate change and that is why winter not reducing global warming effect but in contrary bring more harm.

Q3) The surround atmosphere contains water vapour. When the radar tries to detect the target, it will also trigger the rotation of the water molecules at the same time. This will lead to an inaccuracy in the signals given out during the detection.

Q4)  Among the 3, air quality problem poses the most serious threat in the short run.
The reason is that the effects of such problem are immediately felt (e.g. rise in CO level in air leads to harmful health effects, sometimes death, within minutes);
whereas effects of the other two are more concerned towards the future (e.g. rise in sea level is not much of a threat now, but could displace many shore-based population in several decades ahead if current trend is kept).

Global warming would pose the most serious threat in the long run.
Some long term threats include,

• More frequent intense droughts that would reduce the supply of agriculture whilst the demand is increasing due to an increased in global population size

• Increase in ocean temperatures which threatens the marine biodiversity and the loss of habitat (e.g. Rising temperatures on the Great Barrier Reef leads to coral bleaching, corals die, loss of habitat for marine life, loss of marine life)

• Rising sea levels which threatens countries such as The Netherlands, where more than half of the country is below sea level, and rising sea levels will pose social and economical problems to the country.

• Reduction in the amount of artic sea ice to a point of complete annihilation.

CM8001 – Application Exercise 3 (8/02/2017)

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  1. From personal experience, state whether these processes are endothermic or exothermic. Give a reason for each.
    a. A charcoal briquette burns
    answer: Exothermic. When charcoal briquette is ignited, it gives out heat.b. Water evaporates from your skin
    answer:
    Exothermic. Water takes in heat from my skin in order to evaporate.c. Ice melts
    answer:
    Exothermic. Ice takes in heat from the surrounding in order to melt.
  2. Chemical explosions are very exothermic reactions. Describe the relative bond strengths in the reactants and products that would make for a good explosion.
    answer:
    Enthalpy change = (sum of bond energy broken, positive value) – (sum of bond energy formed, negative value)
    Explosion is an exothermic reaction with a negative enthalpy. A good explosion needs to have a large negative enthalpy.
    Hence, the bond strength of reactants has to be smaller than that of the products.
  3. How might you explain the difference between temperature and heat to a friend? Use some practical, everyday examples.
    answer:
    a. Heat is the total energy of molecular motion in a substance while temperature is a measure of the average energy of molecular motion in a substance.
    b. Heat is energy while temperature is not.
    c. Heat depends on the number and speed of particle while temperature does not.
    Examples: Temperature of a small cup of water might be the same with water in a large tub. However the large tub of water has more heat because it has more water, thus has more total thermal energy.
  4. A premium gasoline available at most stations has an octane rating of 98. What does that tell you about:
    a. the knocking characteristics of the gasoline?
    answer:
    The gasoline has the knocking characteristics similar to the combination of 98% of iso-octane and 2% heptane.b. whether the fuel contains oxygenates?
    answer:
    The presence of oxygenated cannot be determined simply by the octane rating as the octane rating only functions to describe the characteristics of the gasoline. An octane rating of 98 can be derived from a mixture of oxygenates such as MTBE, Methanol or ethanol with octane, or heptane and it can also be derived from a mixture of isooctane with octane or heptane which are both not oxygenates.