Observations of Chemical Changes

Topics: Chemistry, Chemical reaction, Chemical substance Pages: 8 (2987 words) Published: February 22, 2011
Experiment 1: Observations of Chemical Changes
Purpose: To observe the macroscopic changes that occur in chemical reactions and attempt to interpret the microscopic changes of the atoms and molecules that allow for the macroscopic changes to happen; and to associate these chemical properties with household products. Also, it is to learn the importance of how to separate mixtures into their component substances by solubility. Procedure: Before starting with the official experiment, it was important that I dilute the chemicals in the Auxiliary Chemical Bag to change the chemicals to the molarity needed for the experiment. First I had to dilute the Hydrochloric Acid that had a molarity of 6 to a molarity of 1. So, I took the 24-well plate and placed 10 drops of distilled water into well A1. I then proceeded to take the Hydrochloric Acid from the Auxiliary Chemical bag that had 6M and carefully added 2 drops to well A1. Next, I stirred the water and the HCl in the well with a toothpick to ensure that the HCl was diluted as much as possible. Then, taking a pipet labeled Hydrochloric Acid, I sucked up the diluted HCl and placed the pipet upside down in a well plate for standby until needed for the experiment. For Ammonia and Sodium Hydroxide, I followed the same procedure that I did for HCl with the exception that the diluted solution for Ammonia was made in well A2 and the diluted solution for Sodium Hydroxide was made in well A3.

Now that the diluted solutions have been created and contained, I must move on the main experiment. In order to conduct this experiment, I must have a 96-wellplate, the diluted solutions in the pipets that contain them that I just created, a piece of white paper, a piece of black paper, and the chemicals from the Observation of Chemical Changes Experiment Bag.

For the following combinations of chemicals, and using a different well of the 96-well plate for each combination, I must place 2 pipet drops of the first chemical in one well and then add 2 drops of the second chemical, unless it is stated otherwise below. After combining the chemicals, I must observe the mixture against white and dark backgrounds by slipping white and black paper underneath the well plate. For ever reaction, I wrote down the chemical combination, the well number, and my observations of the chemical reactions against the white and dark backgrounds. The combinations are as follows: a)NaHCO3 (sodium bicarbonate-baking soda) and HCl (hydrochloric acid)* b)HCl* and BTB (Bromthymol blue)

c)NH3 (ammonia, a base) and 1 drop of BTB
d)HCl* and FDC Blue Dye#1
e)FDC Blue Dye#1 and NaOCl (sodium hypochlorite). Observe, then add 1drop of HCl. f)NaOCl (sodium hypochlorite) and KI (potassium iodide). Observe, then add 1 drop of starch (shake well before using). g)KI and Pb(NO3)2 (lead nitrate)

h)NaOH (sodium hydroxide – a base)* and phenolphthalein. i)HCl* and phenolphthalein
j)NaOH and AgNO3
k)AgNO3 and NH3(ammonia)*
l)NH3* and CuSO4(Copper(II)sulfate)
After placing all the liquids in the well, I made sure to use a toothpick to stir up the chemical and recorded as many observations as I could. Data Tables: (These data tables include observations)

Chemical Reaction w/White Paper(Observations)
Chemical Reactions w/Black Paper
NaHCO3 (sodium bicarbonate-baking soda) and HCl (hydrochloric acid)*A1Clear bubbles; bubbles did not fizz and continued to occur until all of the liquid from the well was gone. Homogeneous. Bleach-like smellClear bubbles; bubbles did not fizz and continued to occur until all of the liquid from the well was gone. Homogenous. Bleach-like smell HCl* and BTB (Bromthymol blue)B1Turned orange, homogenousTurned into an amber color, homogenous NH3 (ammonia, a base) and 1 drop of BTBC1Turned dark blue, but did not leave a stain on the toothpick; homogenousStill resembled a dark blue, NOT black; did not leave stain on toothpick; homogenous...
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