Q1) 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.

Ans:There are a few methods to purify water while hiking.

The first method is to boil the water. Boiling can kill many microorganism that might cause one to sick. However, it requires time and does not remove chemical contamination. Boiling also requires fuel and will release soot and CO₂.

The next method is to purify the water with iodine. It is an easy and effective method that requires only 20 minutes. However, iodine should not be used long term. Pregnant women and people with thyroid conditions should avoid this method of purification. Iodine renders water bacteriological safe, but it does not remove chemical contaminants. Also, many people does not like the taste of iodine-treated water.

The third method is to purify the water by using a filtering device. Filtration has the advantage of not requiring any chemicals and remove the most microorganism that cannot be killed by boiling or iodine treatment. A good filter can pump out clean water in a few minutes and is reusable.

The most expensive method will be filtering device followed by iodine and lastly boiling of water.

The price of the method is proportionate to the effectiveness of the ability to give clean water.

• 1 being the most expensive and 3 for least expensive for cost.
• 1 being most effective and 3 for least effective for the ability to remove microorganism.

Q2) Explain why desalination techniques, despite proven technological effectiveness, are not used more widely to produce portable drinking water.

Ans:The two most commmon desalination techniques are distillation and reverse osmosis. 

Both the techniques require energy to remove salts from seawater or brackish water, and thus inherently are expensive.

If a less expensive option is available, such as hauling fresh water, it would be used instead.

Q3) 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?

Ans: The most likely major source of the lead in the drinking water is from solder in the pipe joints or from lead pipes itself.

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

Ans: Research activities should not contribute to lead in the drinking water, assuming that any lead compounds are not dumped down the drain. 

Although many undergraduate chemistry experiments used to use lead compounds, most now have been redesigned to avoid it and other toxic metal ions. The substances dumped into a sewage treatment system might end up downstream into someone else’s drinking water.

Q4) Some vitamins are water-soluble, whereas others are fat-soluble. Would you expect either or both to be polar compounds? Explain.

Ans: Only water-solble vitamins would be expected to be polar molecules. Though a fat-soluble vitamin will often have individual polar bonds or small regions of the molecule, overall this out-weighed by non-polar sections. Polar covalent bonds attract to water through hydrogen bonding and may allow the molecules to dissolve in water, while non-polar covalent bonds favor interactions with the non-polar chains in lipids.