NAMES OF PARTICIPATING GROUP MEMBERS

This is a group quiz (no more than 3 per group); closed book and notes!

1. (30 pts) Last week, all groups solved the "grams/moles/millimoles" problems correctly. Now just to make sure everyone has this basic aspect of chemistry, you will each take an individual quiz on it AFTER you have done this group part of the quiz. (Notice: if you do not understand the "grams/moles/millimoles" material, before you part company from your group members, get them to teach you.)

2. (10 pts) The lab which you are about to do deals with the determination of the voltages between wires of two different metals that are stabbed into a lemon or lime. Using the word "affinity," give the basic idea behind this lab exercise.
   
   The atoms of the different elements vary in regard to their affinities for their electrons. In our protocol, we match up pairs of elements to see which one will more easily release an electron to the other. The element that loses the electron has a lower affinity for it.
   

3. (5 pts) When an atom gains an electron, it is said be be "oxidized" or "reduced." (Circle the correct word.)
   A mnemonic: since an electron is a negative charge, if you add a negative to something it goes down or is "reduced."

   

4. (20 pts) On the reverse side of the page, draw a titration graph showing the buffer solution of HPO₄⁼/H₂PO₄^- such that
   1. the pKa = 6.9, and
   2. the pH varies between 5 and 8.5, and
   3. with pH being on axis, and what is on the other axis, and
   4. what is the predominant ion (HPO₄⁼ or H₂PO₄^-) at pH 6.4 and pH 7.4.

5. (5 pts) Drain-O's main active ingredient is concentrated NaOH, which can slowly degrade proteins such as hair, and react with oils and fats to solubilize them and thus break up clogs. Yet, a large slug of solution at extremely high pH goes down the drain and into our rivers. How come this influx has essentially no effect on the river's pH?
   
   Surface waters have a lot of dissolved CO₂ in them. Another name for dissolved CO₂ is carbonic acid, H₂CO₃, which as a weak acid nevertheless neutralizes the base. There are other acids and buffers common in both fresh and saline surface waters.

6. (15 pts) Synonyms and antonyms
   1. If an aqueous solution has a pH = 1, give a noun and an adjective that describes that solution.
      acid
      acidic
      
   2. If an aqueous solution has a pH = 13, give two nouns and two adjectives that describe it.
      base, alkali
      basic, alkaline, caustic

   3. (10 pts) What is the molar hydrogen ion concentration when the pH is neutral?
      1X10^-7 M