Tag Archives: Application Exercise

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

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)

  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.