The objectives of this experiment are:
1. To observe some properties of chemical reactions
2. to associate chemical properties with household products
Background Information:
Chemical changes are often accompanied by physical changes. Three that you should not see in this lab are changes in temperature, presence of a flame, and evolution of light, as when as firefly glows. Three physical changes that indicate a chemical change may have occurred (and that may be seen in this lab) are:
1. Color changes
2. Precipitate (formation of a solid)
3. Formation of gas bubbles
Procedure:
No preliminary dilution of my test chemicals were necessary as Lab Paq provided pre-diluted chemicals. Utilizing the 96-well plate, 2 pipit drops of each chemical were added to the wells in the following combinations: a) NaHCO3+HCl b) HCl+Bromthymol blue c) NH3+1 drop Bromthymol blue d) HCl+blue dye e) Blue dye+NaOCl followed by HCl f) NaOCl+KI followed by various test foods g) KI+Pb(NO3)2 h) NaOH+phenolphthalein i) HCl + phenolphthalein j) NaOH+AgNO3 k) AgNO3+NH3 l) NH3+CuSO4. Along the way, observations were made pertaining to the reactions witnessed. This experiment concluded with testing household chemicals and proper disposal of lab chemicals.
The Term Paper on Observations of Chemical Changes 2
... lab exercise I was given the task of observing chemical changes. I observed double replacement reaction, precipitation reaction, reactions between various chemicals with Bromothymol Blue ... and BTB NH3 + C27H28Br2O5S ? NH4+ + OH- (unknown) HCl and Blue Dye H+Cl- + C37H34N2Na2O9S3 ? H3O+ + Cl- + (unknown) Blue Dye and NaOCl C37H34N2Na2O9S3 + NaOCl ? + + (unknown) Kl ...
Observations:
CHEMICALS Well # Reaction on white paper Reaction on dark paper a. NaHCO3 + HCl A1 Bubbling Clear Liquid Bubbling Clear Liquid b. HCl + BTB B1 Golden Yellow Clear Liquid Amber Clear Liquid c. NH3 + BTB C1 Royal Blue Clear Liquid Dark Blue Opaque Liquid d. HCl + blue dye D1 Emerald Green Clear Liquid Dark Green Opaque Liquid e. NaOCl + blue dye E1 Bright blue that dissolved to yellow Same; just easier to see then to pale yellow.
