1.How can you purify your water when you are hiking? Name two or three possibilities. Compare these methods in terms of cost and effectiveness. Are any of these methods similar to those used to purify municipal water supplies? Explain.
1) Boiling Water in a pot over a fire
2) Filtration
3) Tablets (Water Purification) Eg. Chlorine / Iodine

However, these cost saving methods does not remove toxic substances & cryptosporidium.

These methods are similar to those being used to purify mineral water but without more toxic substances + contamination + testing of the substances are done before it is discharged to public.

2.Explain why desalination techniques, despite proven technological effectiveness, are not used more widely to produce potable drinking water.
It requires a huge amount of energy to distill very little amount of pure water. In addition, there are still a lot more of impurities in water such as bacterial and organisms and unwanted chemicals, as a result, the water has to go through treatment.
As such, the water treatment cost will become costly and high pressure equipment requires a lot of energy.

3.Water quality in a chemical engineering building on campus was continuously monitored because testing indicated water from drinking fountains in the building had dissolved lead levels above those established by NEA.

a. What is the likely major source of the lead in the drinking water?
Corroded pipe, rust.

b. Do the research activities carried out in this chemistry building account for the elevated lead levels found in the drinking water? Explain.

No. Waste water pipes and water supply pipes are independent. Also, before water is discharged to public for drinking, levels of contaminants will be checked.

4. Some vitamins are water-soluble, whereas others are fat soluble. Would you expect either or both to be polar compounds. Explain.

Water-soluble vitamins have polar groups hence they are polar, they can undergo hydrogen bonding with water.
Fat-soluble vitamins are non-polar, they can only dissolve in non-polar solvents.

 

1. Understanding Earth’s energy balance is essential to understanding the issue of global warming. For example, the solar energy striking Earth’s surface averages 168 watts per square meter (W/m^2), but the energy leaving Earth’s surface averages 390 W/m^2). Why isn’t Earth cooling rapidly?

Some heat energy trapped by clouds and atmosphere, even though it is reflected off earth’s ground surface.

2. Decide and explain whether the statement is correct or incorrect. Explain.

Incorrect.The extreme winter is a result of global warming which should be a cause of concern as more extreme winters will have devastating consequences on traffic/temperature/crops etc.

3. One of the first radar devices developed during World War II used microwave radiation of a specific wave range that triggers the rotation of water molecules. Why was the design not successful?

The radiation warms up drinking water/liquid items unnecessarily. Food gets cooked/ might explode (eggs) due to the heat energy.

4. Now that you have studies air quality (Unit 1), stratospheric ozone depletion (Unit 2), and global warming (Unit 3), which do you believe poses the most serious problem for you in the short run (pick one and explain)? In the long run (Pick one and explain why)?
Short run – Air quality as it affects health directly like respiratory issues. Also affects road/air traffic vision.
Long run – Ozone depletion as it is a cause of global warming as well. Causes serious medical issues in the long run like skin cancer due to increased and more intensive exposure.

Question 1: From personal experience, state whether these processes are endothermic or exothermic. Give a reason for each.

A. Exothermic, gives out heat

B. Endothermic, takes heat in to evaporate

C. Endothermic, takes in heat to melt

Question 2
Chemical explosions are very exothermic reactions. Describe the relative bond strengths in the reactants and products that would make for a good explosion.

Bond breaking that occurs in an reactant would be Endothermic, whereas bond formation that occurs in an reactants would be Exothermic.

To produce a good explosion, the bond strength of the products should be much stronger as compared to the reactants.

y are released.

 

Question 3:
How might you explain the difference between temperature and heat to a friend? Use some practical, everyday examples?
An object with no heat energy still has a temperature of 0K (Kelvin). Temperature is a measure of heat inside a medium.
Heat is measure of temperature transfer from warm to cold area.
An oven set at 200°C provides heat energy to food to raise its temperature to 200°C

– In a situation of a unfortunate event where a person burn his skins from a cup of hot water, the area of the skin where the hot water touches will experience burning sensation. This is due to the presence of heat / heat content. As heat is a form of energy, it flows from a point of higher temperature to a lower temperature
( If you put your hand into hot water, you will feel hot, this is due to the presence of heat)
*Cold water – lack of heat, feels cold.

 

Question 4:
A premium gasoline available at most stations has an octane rating of 98. What does that tell you about:

The knocking characteristics of this gasoline?
a) 98% is octane and 2% heptane

Whether the fuel contains oxygenates?
b) might contain premium gasoline and expensive due to addition of oxygenates which are costly. The octane rating is also relatively high so it is possible that it is enhanced.
Might not contains oxygenates usually for gasoline with octane ratings exceeding 100.

 

Group 7 Topic!