Fluids and Polymer Chemistry - "Slush Powder or Lighting Gel"

Standards

NSES Content Standard B – Chemistry: Structure and properties of matter, chemical reactions, interactions of energy and matter – Grades 9-12

Understanding of the microstructure of matter can be supported by laboratory experiences with the macroscopic and microscopic world of forces, motion (including vibrations and waves), light, and electricity. These experiences expand upon the ones that the students had in the middle school and provide new ways of understanding the movement of muscles, the transport of materials across cell membranes, the behavior of atoms and molecules, communication technologies, and the movement of planets and galaxies. By this age, the concept of a force is better understood, but static forces in equilibrium and students' intuitive ideas about forces on projectiles and satellites still resist change through instruction for a large percentage of the students.

Misconceptions

• Objects float in water because they’re “lighter” than water.

• Objects sink in water because they’re “heavier” than water.

• Mass, volume, weight, heaviness, size, and density may be perceived as equivalent.

• Wood floats and metal sinks.

• All objects containing air float.

• Liquids of high viscosity are also liquids with high density.

• Adhesion is the same a cohesion.

• Heating hair only makes it hotter.

• Pressure and force are synonymous.

• Pressure arises from moving fluids.

• Moving fluids contain higher pressure.

• Liquids rise in a straw because of “suction.”

Fluid pressure only acts downward.

Activity

Slush Powder, Lightening Gel, it goes by lots of manes (Magicity.com, product number 20-1233, $14.99). The activities and fun are endless. To make disappearing water work, the magician takes a glass of water from an audience member close by and visibly pores the water (any liquid works) from its original cup into a second cup. Some magic words are spoken over the second cup and the water is pored back into the first cup. The catch is that as the second cup is tipped to pour the water back, nothing comes out. It has magically disappeared.

The illusion takes a bit of preparation but if mastered, can be done in plane sight. The magician takes a glass of liquid from and audience member and pores it, in plane sight, into a cup that contains about ½ a teaspoon of sodium polyacrylate, otherwise known as lighting gel or slush powder. The powder will instantly absorb the water (liquid) and render it solid enough not to pour back out when the cup it tipped. This is a very fast reaction and it only takes a small amount (1 teaspoon for 8 oz of water) of lightening gel to make the illusion come to life.

It’s not magic, it’s science!

This activity focuses students’ attention on the ideas that liquids have different viscosities, adhesion is different from cohesion and can be a powerful force, and polymers are huge molecules that can form very rapidly under the right conditions. Studying the chemistry behind polymer reactions is another great way to continue the discussion beyond the demonstration. As was stated above, Lightening gel, offers a great number of fun and easy illusions limited only by your imagination.