Title: Observations of Chemical Changes
Purpose: To observe some properties of chemical reactions and to associate chemical properties with household products.
Procedure: In this experiment I used a 96-well plate to hold each of the chemical reactions that occurred during this lab. Using a pipet, I added two drops of one chemical with two drops of another chemical and observed the effects of each reaction.
Data Table 1: Experimental Data
Well #| Chemicals| Observations|
| | Reaction| White paper| Dark paper|
A1| NaHCO3 and HCl-CO2| Bubbles formed from CO2 emissions| Clear solution| Clear Solution| B1| HCl and BTB| Solution changed from clear to orange| Orange solution| Orange solution| C1| NH3 and BTB| Solution changed from clear to blue. | Blue solution| Blue solution| D1| HCl and blue dye | Solution changed to Green| Green solution| Green solution| E1| Blue dye and NaOCl| Solution remained Blue. When HCl is introduced, solution turned blue green | Blue-green solution| Blue-green solution| F1| NaOCl and KI| Solution changed from clear to Green, with the addition of Starch, the solution turned Black| Black solution| Black solution| G1| KI and PB(NO3)2| Yellow precipitate formed | Yellow solution| Yellow solution| H1| NaOH and Phenolphthalein| Solution changed from clear to Purple-red| Purple-red solution| Purple-red solution| A7| HCl and Phenolphthalein| No reaction. No color change with Acids. Should turn a reddish color with bases| Clear solution| Clear solution| B7| NaOH and AgNO3| No reaction| Clear solution| Clear solution| C7| AgNO3 and NH3| No reaction | Clear solution| Clear solution| D7| NH3 and CuSO4| Blue precipitate formed| Blue solution| Blue solution|
Data Table 2: Presence of Starch in Food
Well #| Food Product | Observations|
| | Reaction Color| Presence of Starch|
A5| Corn| Green-black | Yes|
B5| Cooked Spanish Rice| Black| Yes|
C5| Grannysmith Apple| Orange| No|
D5| Sundried Tomato| Orange| No|
E5| Cornchip| Yellow| No|
F5| Sharp cheddar cheese | Black| Yes|
A. I added a few drops of hydrochloric acid to see if CO2 is produced, in order to test a household product that states it contains sodium hydrogen carbonate. B. Common household items and Bromothymol Blue
Well #| Household Product| Observations|
A10| Windex| Acidic – solution is blue|
B10| Foaming mint hand soap| Acidic – solution is blue| C10| Clorox Bleach| Basic – solution is yellow|
D10| MonsterEnergy Zero Ultra | Neutral – no reaction| E10| Sutter Home Chardonnay| Acidic – solution is blue| F10| Vinegar | Acidic – solution is blue |
As the table above indicates, both strong bases and acids are effective household cleaners. C. I would assume that the sample solution is vinegar because phenolphthalein turns pink in the presence of an acid. D. My interpretation is that the fifth sample did not contain starch. E. I would assume that the yellow flavor is basic and the blue flavor is acidic. F. I would drop a few drops of potassium iodide into the tonic. If a yellow precipitate is formed, then I know there is lead in the hair tonic.
Conclusion: Initially this experiment was confusing because the NaOCl and KI were not reacting with the starch as expected. I realized that the KI was not the problem because it formed the precipitate with PB(NO3)2 as expected; therefore, I deduced the NaOCl supplied by labpaq was not reacting properly. After determining that NaOCl was household bleach, I went to the laundry room, got some bleach, performed the tests again and obtained the expected reactions. That was very satisfying! Also, I’ve recently gone on a health kick, and identifying whether a food contains starch is important to me now because I am trying to cut back on my starch intake to lose weight. Perhaps I should take the labpaq to the restaurant!