In Singapore’s context, Singapore is a port and thus, sea space is highly important for our economy. Desalination plants are required to be near the ocean so as to draw water from the sea, causing such plants to take much of Singapore’s sea space. Desalination plants require a lot of heat to produce drinking water, so large amount of fuel resources are required, making it unsuitable to be widely used in Singapore.

In a worldwide context, distillation is an expensive process making it unsuitable to produce potable drinking water in countries that lack economic power.

Water-soluble vitamins are polar compounds while fat-soluble vitamins are non-polar. This is due to “like dissolves like”. Polar compounds, such as water-soluble vitamins, tend to dissolve well in polar solvents (ie. water). Fat-soluble vitamins are non-polar due to the large amount of phospholipids present, making it hydrophobic and therefore water-insoluble. They are instead soluble in fat, which are non-polar, due to their non-polar interactions.

a. Hanging your laundry to dry, instead of using a dryer, uses lesser electricity and thus saves on the amount of fuel used.

b. Walking, biking or taking public transportation to work will reduce the amount of fuel-usage and thus reduce the emissions of NOx and SOx.

c. Running dishwashers and washing machines with small loads will require us to run these appliances more frequently and thus, uses more electricity.

d. Adding insulation allows heat transfer to be more efficient and thus reducing the amount of heat wastage and the amount of electricity needed to generate heat.

e. Buying locally grown produce will reduce demand for imported food. Importing food from foreign countries requires air transportation and thus uses up jet fuel. By importing less food, the country can save on the amount of fuel used and thus reduce the emission of SOx and NOx.

a. Power plant can produce water vapor, sulfur oxide and even ash, if not collected properly. Burning of coal usually results in incomplete combustion and this releases soot into the air, causing smog to be formed and thus leading to poor visibility in the area.

b. The pH of natural rain is 5.6 and for every drop in pH unit, the acidity of the solution increases by 10 times. Thus, the pH of the rainfall in the park should be 4.6.

a. Exothermic. Process requires a larger amount of energy to form bonds than to break bonds. Energy of Products is lower than that of reactants.

b. Endothermic. Process requires a larger amount of energy to break bonds than to form bonds. Energy of products is larger than the energy of reactants.

c. Endothermic. Process requires a larger amount of energy to break bonds than to form bonds. Energy of products is larger than the energy of reactants.

In the reactants, the total bond strength should be lower than that of the products. This is because lesser energy is needed to break all the bonds in the reactant than the energy needed to form all the bonds in the products. In this way, only can the reaction be exothermic. Furthermore, the product needs to be a gas in order for the volume to expand drastically during the explosion.

Heat is a form of energy transfer – energy that flows from a hotter to cooler object. Heat is a consequence of motion at the molecular level, while temperature is a measure of the average speed of that motion. Heat is what we can feel with our senses, whereas temperature is a more specific measure of how hot object is.

For example, a pot of boiling water has a temperature of 100 degree celsius while ice has a temperature of 0 degree celsius. However, ice contains more energy or heat compared to a pot of boiling water.

a. It tells us that it has a knocking characteristic of 98% iso-octane and 2% of heptane.

b. Oxygenates are compounds that assist in the combustion in engines and help reduce co-emission and reduce knocking. The octane rating can be increased in the presence of oxygenates however the octane rating itself does not tell us whether the fuel contains oxygenates.