Tag Archives: AE Answers

Collection of Application Exercise Answers

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 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 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.