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Why the Tricks Work

Crystal Creation

The water-sugar solution prepared by your teacher was made with hot water. When the solution cooled, it was holding "extra" dissolved sugar. As water in the glass evaporates, some of this extra sugar can no longer remain dissolved. It comes out of solution and forms sugar crystals. Crystals will naturally attach to a solid in the solution (the strings). Over time, as water continues to evaporate, more sugar will come out of solution and the crystals will increase in size.

The Great Burnout

Soda water is a solution of carbon dioxide gas and water. In a closed bottle, pressure causes the carbon dioxide to remain dissolved. Removing the cap from the bottle releases the pressure, allowing carbon dioxide to form bubbles, which rise to the surface and escape from the solution. When you pour soda water into a glass, a thin layer of carbon dioxide forms just above the surface of the liquid. A burning match placed in this layer of gas goes out because there is not enough oxygen to keep it burning.

Parting Pepper

Surface tension creates a thin film on the surface of the water. Pepper grains don't disturb the surface tension, so the grains float quietly on the surface of the water. A very small amount of detergent breaks the surface tension, causing the water molecules to move apart, carrying the grains of pepper with them.

Dissolving Pictures

The liquid prepared by you contains a small amount of turpentine, which doesn't mix readily with water. Adding soap helps the water and turpentine to mix. The turpentine in the mixture dissolves some of the ink used to produce the newspaper picture. When the white sheet of paper is pressed against the newspaper, the dissolved ink -and the picture- is transferred to the sheet of paper.

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