Water, Soap, and Chlorine
Topics for Discussion
As you investigate, please be sure to collect the information below for discussion. Keep in mind this is NOT a copy/paste activity (penalty for plagiarism is severe!). You will likely have to consult several sources to find all this information in sufficient detail.
(1.) Water is ubiquitous and necessary for life on our planet. Describe the numerous unique properties of water and how it supports life. With specific applications to humans, what are the most common chemical contaminants of municipal water supplies in the country in which you reside? Why? What properties do these chemicals possess that allows them to be easy contaminants, and what risk do they pose to humans? Is access to clean drinking water a basic human right, do you think? Or is it merely a luxury? Why or why not? Be sure to answer all these questions in order to receive credit.
(2.) How do soaps work, chemically speaking? Describe their chemical properties and give an example (including chemical formula) of a particular soap.
(HINT: In order to help visualize this, you may want to grab a couple of clean cups and fill them say 1/2 of the way with water. In one of the cups, simply sprinkle some pepper on top. In the other cup, finish filling it up with vegetable or cooking oil. Put a drop of dish soap on your finger tip and lightly touch the center of the water’s surface in cup with the pepper. What happened? In the other ½ water ½ oil cup, notice what it looks like. Stir it up, and make the same observation. Now, in that cup, place a few drops of dish soap. What happened? Also fun is the following: Take a small amount of aluminum foil and fold it into a boat. Set the boat in a clear large pan or bowl of clean water. Note your observation. Then, place a drop of dish soap on your finger, pick up the boat, then apply the soap gently to the back of the boat, and set the boat back down at the edge of the bowl/pan. What happened? Why? CONSIDER ALL OF THESE OBSERVATIONS AS YOU TRY AND ANSWER THE DISCUSSION QUESTION.)
(3.) Chlorine gas (Cl2) is a gas at room temperature that can kill you if inhaled. When chlorine atoms bonds to other atoms, however, the resulting compounds have their own and completely different/unique properties and uses.
(A) For example, table salt contains chlorine atoms, yet it doesn’t kill us if we consume it (well, at least in moderation!). Describe the chemical properties of table salt (NaCl). As you construct your response, try putting some table salt in a cup of water, and then try putting some into a cup of vegetable or cooking oil. Stir them both. What’s the difference in terms of what you notice? How does this demonstrate the properties you explain? Be sure to answer all of these questions in detail to receive credit.
(B) By mixing chlorine gas with sodium hydroxide (NaOH), a.k.a. lye, you create sodium hypochlorite (NaOCl). NaOCl mixed with water is your common household bleach. Bleach is usually used as a disinfectant. Why? BE SPECIFIC HERE