==Colorful Chemical Clues==

A variation on a theme: Do "The Rainbow Reaction" as a post-lab demo; use 
cabbage juice indicator. Works great!

Two "half-cell" reactions:

2H20 --> 2H2(g) + 2OH  <<== cabbage juice will turn green

2H20 --> O2(g) + 4H  <<== cabbage juice will turn magenta

==
- Pre-lab Demo: "The Rainbow Reaction"
http://www.wsanford.com/~wsanford/gr8ps/01_green/
09_colorful_chemical_clues/extras/rainbow-reaction/

> Acids & Bases - "Colorful Chemical Clues" (C3) - Part 1: The Tests (pp.
79-85); Part 2: Presto Change-o (pp. 86-92). Note: Part 2 features
"Analysis" questions re: writing & balancing chemical equations.

Provisioning: Need ~150ml cabbage juice per class for both Parts 1 & 2. 
- See msg. (under separate cover) re: provisioning for lab (groc. store
list)
- Use 2,000 mL flask to "brew" batch of "Purple Rain" (in honor of the
artist formerly known as, "Prince"). 1/4 red cabbage per liter of water
(use 1/2 cabbage for 2L). Simmer on hotplate (low) for several hours.
Decant liquid; use plastic (or glass) stirring rod to extract cabbage
leaves from flask. Refrigerate.
- After C3 - Part 1, recover ammonia and vinegar for use during Part 2
(Presto Change-o).

Other considerations...
- To avoid cross-contamination, use same containers from year-to-year:
plastic vials for samples; droppers & dropper-holder vials.

Note: Litmus paper is impregnated with an extract from lichens. Lichens 
"straddle" two kingdoms: the plant kingdom; and the fungi kingdom. [What 
did the boy mushroom say to the girl mushroom? I'm a fungi (fun guy)!]

Fill each well 3/4 full with each of the seven (7) common household 
solutions; add ten (10) drops of cabbage juice in each well.

Show video segment(s) related to activity questions, GSLG p. 82, #3b and 
#4b.
"Acids, Bases, Salts, and Solutions"
SMS Library video
18 minutes
Acids & Bases: pH scale
0:00:00 - 0:06:39
Salts: balancing equations, acid + base = H2O + salt, electrolytes
0:06:39 - 0:10:57

--
C3 - Part 2: Presto Change-o

Provision approx. ~1 L (for three classes) of vinegar (v), cabbage juice 
(c), ammonia (a). "c"  stands for both _c_abbage juice and _c_ontrol. 
Modified lab procedure directions -- use medicine cups to fill each test 
tube w. 10 ml cabbage juice. (In practice, it's easier to mix liquids 
using slightly smaller initial volume.) Demo Dr. V's technique for mixing 
liquids in a test tube. Seven (7) 250 ml beakers of three (3) liquids 
(v,c,a) shared among 14 stations: 42 test tubes; 14 test tube racks, 3 
tubes per rack. Fill beakers to 100 ml (in case of spills); refill as 
necessary.

The products of a neutralization reaction (reactants = acid + base) are 
water and a salt. [Did you hear about the peanut walking down the street? 
It was assaulted (a salted).]

==
Use the following activity from "Chemistry w. Computers":

   21 - Household_Acids.xmbl

(x) Collaborate w. DrV to create data files. Use UNUSED solutions to 
measure pH.

Note to self re: summary question, CCC Part 2:
HCl + NaOH = HOH + NaCl
Note: NaOH = sodium hydroxide, a.k.a., lye