*Also get out Assignment #47 (pH WORKSHEET) to be stamped. Warm Up: Open your notebook to pages 126-127. On page 126, copy the following and predict the next numbers. 2, 4, 8, 16, 32, 64, ___, ____ 100, 10, 1, 0.1, 0.01, ____, ____ *Also get out Assignment #47 (pH WORKSHEET) to be stamped.

Red Cabbage Lab/ Serial Dilutions Now write the title shown above and Objective shown below on pages 126-127, and update your Table of Contents. (In a minute, you will record the revised lab instructions on page 127.) OBJ: Perform serial dilutions; obtain and evaluate experimental data from red cabbage juice color change.

Pause for a thought experiment. Imagine you had 10 mL of a very concentrated, deep blue solution. (See left-most beaker.) Then you placed 1 mL of that solution into the next beaker, added 9 mL of water and mixed. You repeat that three more times. Would the results shown to the right (colors & molarities) make sense? Why or why not? What connection can you make with this diagram and your warm-up exercise? Draw a picture of this “serial dilution” diagram on the first ~six lines of ICN page 127.

Modifying lab handout directions. X-out Directions 2 through 4 and 6 through 8 on your lab handout. On #5 change “In Test tube four” to “In Test tube six.” Make a box on your lab handout to the right of the Red Cabbage Color changes with pH diagram and label it Lab Station #. (Odd #’s will begin with Solution A & Even #’s will begin with Solution B.) Write the following in your lab notebook (ICN page 127): (Please DO put this into your own words!) 1st: Rinse your 5 test tubes with small volumes of distilled water. (Dump waste in shared waste beaker.)

Set up your station.  If your lab station number is an odd number, 2nd: Get (if needed) acid or base in your small beaker.  If your lab station number is an odd number, get Solution A (fill beaker ~one-quarter to half-way).  If your lab station number is an even number, get Solution B (fill beaker ~one-quarter to half-way). 3rd: Get (if needed) a paper towel (set up so that you use the paper towel to label the test tubes and fresh cabbage juice— note that water and cabbage juice are shared with neighbors.

4th: Set up your test tubes with solutions – write details into lab handout “Type of Solution” column on data table. (5th: Add a row for Test Tube 6.) Test Tube Type of Solution *STIR each solution well before taking drops for next tube! Initial Observations* *First moment after adding cabbage juice! Red Cabbage Solution Color in tube* *2-3 minutes after adding cabbage juice! pH 1 “TT #1” 40 drops of Solution ____ (A or B) 2 “TT #2” 4 drops from TT #1 & 36 drops H2O 3 “TT #3” 4 drops from TT #2 4 “TT #4” 4 drops from TT #3 5 4 drops from TT #4 6 20 drops Sol’n. A & 20 drops of Sol’n. B

6th: Add cabbage juice to each test tube. 6th: After all the test tubes are set up with solutions… Add cabbage juice until you ~fill each test tube (work carefully to avoid overfilling). Swirl and watch for color change. Record observations in your data table. Compare with colors shown next—see if you can get a pH color match!

7th: Clean up! Clean up. Throw away your paper towel, empty and rinse each test tube into shared waste-–never put chemicals down the sink! Leave your lab stations cleaner than you found it! In your ICN (page 127), rate yourself on how clean you left your lab station.