Month: February 2017

1. Method 1: Filtration using available materials around us (e.g gravel/rocks, coarse sand, charcoal, cloth and a plastic water bottle). set up the filtration as shown in the diagram below.

Method 2: Distillation. Set up distillation method as shown in the diagram below. Boil the water over a fire and collect the water droplets which condense on the plastic sheet. The water obtained is pure water.

Filtration is more cost and energy efficient whereas distillation is more energy consuming and non-economical. However, distillation produces water of higher purity.

Filtration is similar to the Microfiltration process in the purification process in NEWater. Distillation is similar to the desalination of sea water to obtain pure water.

2. Despite proven technological effectiveness, desalination techniques such as reverse osmosis and distillation are considered to be expensive and energy consuming, hence it is only practiced in richer countries.

3a. The likely major source of the lead in the drinking water maybe due to the corrosion of lead pipe, or solder from the drinking fountains and water tanks.

3b. Probably not, because all of the research activities conducted in the building usually have strict practice and proper waste disposal cans for the disposal of heavy metals, it is very unlikely that the research activities conducted contributes to the elevated lead levels in drinking water. However, human error may occur sometimes.

4. According to the “like dissolves like” assumption, we expect that the water-soluble vitamins are polar as they are soluble in polar solvents like water. On the other hand, the fat-soluble vitamins are non-polar as they are soluble in non-polar molecules like fats(hydrocarbon chains of fats are non-polar).

1. Greenhouse gases trap the Earth’s infrared radiation. So, the atmosphere keeps the Earth warm.
2. Global warming is a long term change. There may be insignificant and inconsistent increases in temperature change in a specific year. However, the increases in temperature change over a period of time may then be more significant to determine that global warming has really occured. So, the statement is not completely accurate because “this winter” only refers to a specific year.
3. There is water vapour in the air. So, the radar using water molecule rotation will be affected by noise from the water vapour, especially on rainy days. The absorption of microwave radiation by water in the atmosphere interferes with the detection of intended objects.
   Also, microwave radiation of a wavelength triggers the rotation of water molecules. This heats up the air around the machine, leading to diseases caused in the operators of the radar.
4. Air quality will affect us in the short run. Air pollution caused by vehicle emissions (NO2, CO, etc) can be hazardous to our health (cause respiratory problems). Global warming will affect us in the long run. It results in an increase in temperature on Earth that leads to rises in sea levels. This will take a long time for it to have a significant impact. So, even though there is no significant impact on us now, we may experience the accumulated effects in the future.

1a. Exothermic. As the burning of briquette produces heat energy.

1b. Endothermic. Heat energy is required to break the water molecules in order for it to enter the gaseous state and evaporate from our skin.

1c. Exothermic. Heat energy is required to break the lattice energy of the ice in order for the ice to melt.

2. The bond strengths of the reactants has to be relatively weaker as to have a lower activation energy for the reaction. In contrast, the bond strengths of the products need to be relatively stronger in order for more heat to be released in the process so as to create an exothermic reaction that would make for a good explosion.

3. Heat is the energy that flows from a hotter to colder object whereas temperature determines the direction of the heat flow.

For example, imagine putting some ice into a cup of hot tea. The ice would melt almost instantly due to the heat from the hot tea. But the temperature of the hot tea would drop, showing the direction of the heat flow from the tea to the ice cubes.

4a. It has a knocking characteristic of 98% isooctane and 2% n-heptane. As a higher grade premium gasoline, it has higher octane rating than other blends sold at other gasoline stations and hence is more resistant to knocking.

4b. The octane rating does not produce any information regarding the presence of any oxygenates and such details should be available on other parts such as labels around the pump.