CHM130 Lab 3

Topics: Chemistry, Sodium bicarbonate, Acetic acid Pages: 4 (1062 words) Published: June 12, 2015
CHM130
Lab 3
Identification of Chemical Change
Name:      Paige Miller    
A.  Data Table (24 points)
Place your completed data table here:
Reactants
Predictions Before 
Combining
Observations After 
Combining
Starch + I2
 I2 will turn Starch black
 I2 turned starch black
Food coloring + NaOCl
 NaOCI will turn blue
 Coloring and NaOCI did not combine, NaOCI separated to the bottom Food coloring + CH3COOH
 CH3COOH will turn blue
 CH3COOH darkened the blue color
Food coloring + NaOCl
+ CH3COOH
 Will remain seperate
 Solutions returned to clear/cloudy, clear
Red cabbage + NH3
 Change to clear
 Turned green
Red cabbage + CH3COOH
 Change to clear
 Turned pink
NaHCO3  + NH3
 Will mix
 Backing soda separated to the bottom
NaHCO3  + CH3COOH
 Will create bubbles
 Bubbled over
Na2CO3  + CH3COOH
 Bubble
 Small fizz, clouded the mixture
MgSO4  + CH3COOH
 Fizz
 Nothing
MgSO4  + NH3
 Mix
 NH3 turned the MgSO4 white
MgSO4  + Na2CO3
 Fizz or cloud
 The two combined and thickened

B.  Follow-Up Questions
1. What type of macroscopic evidence for chemical change did you observe during this experiment? Give at least three different examples. (15 points) - The food coloring + CH3COOH darkening in color, food coloring + NaOCI + CH3COOH returning to clear, red cabbage + NH3 turning green, red cabbage + CH3COOH turning pink, NaHCO3 + CH3COOH bubbling over, Na2CO3 + CH3COOH fizzing and turning cloudy, MgSO4 + NH3 turning white, and the MgSO4 + Na2CO3 becoming thick are all examples of macroscopic evidence for chemical change. 2. Which reactions, if any, do you believe showed no evidence of chemical change? Justify your reasoning.  (15 points) - I believe the food coloring + NaOCI show no evidence of chemical change because they would not combine. I think that the properties of bleach that allow it to remove stains (color) from things are the same properties that disallow them to combine and have a reaction or change. 3. When two...
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