Month: February 2017

1. Boiling the water should kill off most bacteria and pathogens. Conversely, we can use iodine tablets to make the water safe for consumption. Boiling requires time and fuel  but is a rather inexpensive method of purifying water. On the other hand, iodine tablets are more expensive but are more convenient. Boiling is similar to the industrial distillation process, as it is the key process in this form of water purification.

 

2. Firstly, it is an energy intensive process which requires many resources. Secondly, it needs to be located near the sea in order to maximise transport efficiency which may not always be a viable option. These limitation are often overcome by using other water purification techniques.

 

3a. Corrosion of lead pipes or solder in drinking fountains or water storage tanks.

3b. No. There are separate pipes for drinking water and waste water. Furthermore, waste products from research activities should be specially handled and safely disposed of.

 

4. Water-soluble vitamins should be polar compounds while fat-soluble vitamins should be non polar. It is important to note that only polar solutes can dissolve in polar solvents such as water. Similarly, only non polar compounds can dissolve in non polar solvents such as fat. Therefore we can come to such a conclusion.

1. From the example, we can see that the amount of energy emitted form the surface is more than the energy striking the Earth’s surface. However, the Earth does not cool rapidly because the Earth’s surface absorbs a great amount of energy from the atmosphere.
2. The understanding of the term “global warming” is wrong. Based on the statement, it assumed that global warming is only about the warming of atmosphere and snowing would mean that global warming is not much of a threat. However, global warming also causes heavier precipitation events such as heavier snow fall or unnatural events like snowing in the middle of summer.
3. The design was unsuccessful because the absorption of microwave radiation by atmospheric water hinders with the detection of intended items.
4. In the short term, air quality is the most serious problem because it has direct adverse impact to our health and it definitely has faster effects as compared to the other 2. In the long run, however, global warming is the most serious problem because global warming carries massive implications for a lot of processes. The detrimental effects of global warming trickle down to other aspects which affects our air quality and our way of life. Global warming will also increase the incidents of extreme weather events such as higher number of typhoons and hurricanes. (Hurricane Katrina :((((( )

1. a) Exothermic, heat is given off because it burns. b) endothermic, gains heat from body heat to evaporate c) endothermic, gains heat from surrounding.
2. Good explosion is a rapid high energy reaction (very exothermic). For this condition to arise, the bond energies of the products have to be larger than those of the reactants. This will lead to a large negative net energy which shows an exothermic reaction.
3. Heat is a consequence of motion at the molecular level while temperature is a measure of the average speed of that motion. An everyday example would be the usage of a metal spoon in a hot soup. The heat of the soup gets transferred to the spoon. There’s a difference in temperature between the bowl of the spoon and the handle of the spoon so heat travels from the bowl to the handle. The higher the heat energy, the faster the transfer.
4. a) An octane number of 98 means a knocking characteristics of 98% of issoctane and 2% heptane. b)The octane rating shows us nothing about whether the fuel contains oxygenates.