Name ______

Period ______

Marshmallow Torture

(Boyle’s Gas Law)

Procedure:

Place one marshmallow in a syringe. Put the plunger at the top of the syringe, seal the tip with your finger again and push the plunger down. (Don’t touch the marshmallow with the rubber stopper!)

  1. What happens to the marshmallows?
  1. What is being increased inside the syringe?
  1. What is being decreased?

Take your finger off the tip. Push the plunger down just until it touches the top of the marshmallow. Put your finger over the tip of the syringe to form a seal. Pull up on the plunger.

  1. What happens to the marshmallows?
  1. What is being decreased inside the syringe?
  1. What is being increased?
  1. Which scientist’s law explains this?
  1. For this law, what variables change? Which variable remains constant?
  1. When the syringe is plugged each time, does the temperature in the syringe change?
  1. When the syringe is plugged and its volume changes, does the number of particles in the syringe change?

Slime

(Polymers)

Materials

  • Elmer's glue (most kinds of white craft glue will work)
  • 2 disposable cups
  • Food coloring (you pick the color)
  • Water
  • Borax Powder (available at most large grocery stores near the laundry detergent)
  • A plastic spoon (for stirring)
  • A tablespoon (for measuring)

Procedure

  1. Fill one small cup with water and add a spoonful of the Borax powder and stir it up. Then set it aside.
  2. Fill the other small cup with about 1 inch (2.5 cm) of the glue.
  3. Add three tablespoons (20 ml) of water to the glue and stir.
  4. Add a few drops of the food coloring and stir it up until mixed.
  5. Now the fun part...Add one tablespoons of the Borax solution you made earlier and stir well. Watch the slime form!
  6. After the slime forms let it sit for about 30 seconds and then pull it off the spoon and play with it!

Tip: Keep your slime away from carpet and your little sister's hair.

Explanation

This POLYMER is unique because it has qualities of both a solid and a liquid. It can take the shape of its containers like a liquid does, yet you can hold it in your hand and pick it up like a solid. As you might know, solid molecules are tight together, liquid molecules spread out and break apart (drops) POLYMER molecules CHAIN themselves together (they can stretch and bend like chains) and that makes them special. Jell-O, rubber bands, plastic soda bottles, sneaker soles, even gum are all forms of polymers.

Chemical Equations

-We start by dissolving some Borax (Na2B4O7.10H2O) in water, which dissociates into sodium ions and tetraborate ions.

(Na2B4O7.10H2O) + H20 = Na + B4O7 + H20.

The tetraborate ion reacts with water to produce boric acid and the OH- ion.

B4O7-2(aq) + 7 H2O <—> 4 H3BO3(aq) + 2 OH-(aq)

The boric acid further reacts with water to form the borate anion.

H3BO3(aq) + 2 H2O <— > B(OH)4-(aq) + H3O+(aq)

So now we have the form of the borate ion that we need. Hydrogen bonds form between the borate ion and the OH groups on the sides of the PVA.