Classification of reactions lab

Need help with my Chemistry question – I’m studying for my class.

This is due midnight the 25th my time:) I wanted to give you a couple days heads up. As always, if you could add any pictures that show work as well that would be great! Any images can be looked up online and if pictures are needed that can’t be found let me know.

Learning objective: Observe the three types of chemical reactions discussed; precipitation, redox, and acid-base neutralization reactions.

Read the material in the text and watch the lectures.

Safety

• This lab has been designed so that there are no safety concerns.

Materials

• Epsom salts (Dollar store or your bathroom cabinet, grocery stores carry it but they have large bags)
• Penny, minted after 1983
• Sidewalk made of concrete or file
• Vinegar
• Red cabbage
• Baking soda

Procedure

1. Precipitation reaction
   • Dissolve soap in water. Use bar soap and not a detergent. The dissolved soap may be a little cloudy but you should be able to see through a cm of it. Make a saturated solution with epson salts. Epson salts can be found at those dollar stores. Add a spoonful to about 50 mL of water. If all of it dissolves, add a little more until some remains undissolved. The liquid with out the undissolved epson salt is a saturated solution.
   • Add a little bit of the saturated epsom salt solution to the soapy water and observe what happens.
2. Redox Reaction
   • Find a penny minted after 1983. File away a portion of the edge until it is obviously silver (you can also scrape the coin on concrete or a rock). It can be a very small portion. Place the penny in small container with vinegar.
   • Closely observe the edge of the penny that was scraped to reveal the silver metal inside.
3. Acid-Base neutralization reaction
   • Take a 3″ x 3″ leaf of red cabbage and blend it with a liter of water. Strain the purple liquid from the solids. This is an pH indicator. If you do not have a blender, you can boil a leaf and get the same colored solution. You may have to use a larger leaf.
   • Make about 50 mL of a saturated baking soda solution.
   • Use small portions for the following:
     • separate a portion of the solution into four containers. One container is the control (nothing will be added, so this is the color of the indicator with water)
       • Container 1 – control container, color of neutral solution.
       • Container 2 – add vinegar until the color doe snot change.
       • Container 3 – add the baking soda solution until the color does not change.
       • Container 4 – using about 10 mL of vinegar add some of the cabbage juice, enough cabbage juice so that the color is easy to observe. Add small portions of the the baking soda solution to the container. Make observations. Continue adding the baking soda solution until the liquid in the container matches the color of container 1 (the color in container 4 may or may not be darker than the color in container 1, but they should be the same color). If the color becomes like container 3, you can add small portions of vinegar.
       • Now have some fun. Make more containers of the cabbage juice and add different household substances to them (sugar, cleaning solutions, etc).

Assignment:

1. What was observed when the saturated epsom salt reacted with the soapy water?
2. What is the chemical formula of the substance in epsom salts? What is it reacting with?
3. Write out the balanced chemical reaction for the reaction of the substance in epsom salts with the soapy water.
4. What was observed when looking closely at the edge of the penny that was filed?
5. The reaction with the penny was the zinc inside the penny with acetic acid (CH3COOH or CH3CO2H). The products are zinc acetate and hydrogen gas. Write out the balanced chemical reaction of zinc with acetic acid.
6. The zinc/acetic acid reaction if a redox reaction. Assign oxidation number to the zinc (before and after it reacts), and the acidic hydrogen of acetic acid, and to hydrogen gas.
7. Using all of these terms, oxidized, reduced, OIL, RIG, loses electrons, gains electron, reducing agent, and oxidizing agent. apply each the zinc reactant or to the acidic hydrogen of acetic acid.
8. Describe the following:
   • Water and indicator
   • Water, indicator, vinegar
   • Water, indicator, baking soda solution
   • Vinegar, indicator, and changes as baking soda solution was added.
   • Your own investigations.
9. You should have observed bubbling along with a color change when adding baking soda solution to the vinegar. Write the chemical reaction for the substance in baking soda that reacts with acetic acid in vinegar.

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