To make an erupting volcano, you will need baking soda, vinegar, a container to hold the volcano and paper towels to clean up the mess. Pour some of baking soda into the container, and then add vinegar. Watch while the volcanic eruption takes place. Explain to students that the baking soda, which is sodium bicarbonate, is a base and the vinegar, which is acetic acid, is an acid. When a base and an acid are combined, they create carbonic acid: an unstable compound that breaks apart into water and carbon dioxide. The fizzy bubbles are carbon dioxide escaping the solution in gas form.
Gather a small beaker or bowl of water, food coloring of any color, a small empty water bottle, 2 tbsp. of cooking oil and dish washing liquid. Add food coloring to the water drop by drop until it reaches the intended color. Pour 2 tbsp. of colored water into the bottle, and then add 2 tbsp. of cooking oil. Place the lid on the bottle and shake hard. Set the bottle down and watch as the oil floats to the top instead of mixing with the water. Explain to the students that oil and water do not mix because oil molecules are strongly attached to each other, and it is the same case for water molecules. Since they are more strongly attracted to their own type of molecule, water and oil don't mix with each other. Oil floats to the top because it has a lower density and is thus lighter in weight than water.
Gather an egg, salt and a tall drinking glass filled halfway with water. Stir 6 tbsp. of salt into the glass of water. Gently pour more water into the glass until it is nearly full, careful not to mix the salty water with plain water. Slowly lower the egg into the water, letting go when it is halfway in the water, and watch what happens. Because salt water is denser than fresh water, the egg floats in the salt water because denser liquid allows objects to more easily float. Thus, the egg passes through the fresh water but is caught by the salty water, which is dense enough to keep the egg afloat.
To make a chemical reaction experiment involving acids and bases, you will need a lemon, water, a tsp. of baking soda, sugar and a drinking glass. Cut open the lemon and squeeze as much juice into the drinking glass as you can. Pour an equal amount of water as lemon juice into the glass.
Put the teaspoon of baking soda into the glass and stir. Add sugar to taste. Watch the drink fizz and bubble. Explain to students that the bubbles are carbon dioxide (CO2), created by the mixture of lemon, which is acidic,and the baking soda, which is basic.