CHAPTER 8: WATER EVERYWHERE: A MOST PRECIOUS RESOURCE These questions cover Chapter 8 – all sections Total point value for this assignment = 30 pts

1. a. What type of bond holds together the two hydrogen atoms in the hydrogen molecule, H2? (2pts)

b. Explain why the term hydrogen bonding does not apply to the bond within H2.

c. Give one example of where hydrogen bonding does occur (name of molecule(s))

2. The maximum contaminant level (MCL) for mercury in drinking water is 0.002mg/L. (2pts)

a. Does this correspond to 2 ppm or 2ppb? b. Is this mercury in the form of elemental mercury (“quicksilver”) or the mercury ion

(Hg2+) ?

3. A solution is prepared by dissolving 0.50 mol NaCl in enough water to form 250 mL of solution. A second solution is prepared by dissolving 0.60 mol NaCl to form 200 mL of solution. Which solution is more concentrated? Explain. (2pts)

4. An aqueous solution of KCl conducts electricity, but an aqueous solution of sucrose does not. Explain. (Hint: do these two molecules dissolve in the same manner?) (2pts)

5. Write a chemical equation that show the release of ONE hydrogen ion from a molecule of

each of these acids (3pts)

a. HBr (aq), hydrobromic acid

b. H2SO3 (aq), sulfurous acid

c. HC2H3O2 (aq), acetic acid

6. Today we are creating dirty water faster than nature can clean it for us. (4pts and don’t quote the text back to me!) a. Name five daily activities that dirty the water.

1 2 3 4

b. Name two ways in which polluting substances naturally are removed from water. 1 2

c. Name five steps you could take to keep water cleaner in the first place. 1 2 3 4

7. Consider a molecule of ammonia, NH3. (4pts)

a. Draw its Lewis structure.

b. Does the NH3 molecule contain polar covalent bonds? Explain.

c. Is the NH3 molecule polar? Hint: Consider its shape.

d. Would your predict NH3 to be soluble in water? Explain.

8. Write a chemical equation that shows the release of hydroxide ion(s) as each of these bases dissolves in water. (2pts) a. KOH (s), potassium hydroxide

b. Ba(OH)2, (s), barium hydroxide

9. Give names and chemical formulas for 4 acids of your choice. Name three observable properties generally associated with acids. (4pts)

10. Write a balanced chemical equation for the following acid base reaction (1pts)

a. Potassium hydroxide is neutralized by nitric acid

11. A 5-minutes shower requires about 90 L of water. How much water would you save for each minute that you shorten your shower? (2pts)

12. A student weighs out 5.85g of NaCl to make a 0.10M solution. What size volumetric flask does the student need? (2pts)