Hands-On Science Activity: - by George Pastirik, President, Science Is... Copyright © 2015
You will need: Large clear container (jar or drinking glass)
Water Vinegar Baking Soda
Raisins, Peanuts, Uncooked Spaghetti
Naphthalene Mothballs (optional)
Food Colouring (optional)
What to do:
Fill the container about 80% full of water, then add enough vinegar to almost fill it up. This is a weak acid solution. Slowly sprinkle half a teaspoon of baking soda into the water/vinegar solution. (Do not dump it in all at once!) The solution will fizz and bubble. When the bubbling slows down, slowly sprinkle in another half teaspoon of baking soda. When most of the bubbling stops, drop some raisins, peanuts and/or uncooked spaghetti (broken into small pieces) into the bubbling solution and wait. (Naphthalene mothballs also work well, but they can be toxic, and resemble candy, so they are unsuitable for use with younger children.) You will see the objects randomly rise to the top of the liquid where they may stay only momentarily or for a minute or two. They will then go to the bottom of the container again. After a short period of time, they will repeat this up and down motion. They will continue this "Bubble Ballet" dance for quite a long time.
Adding baking soda to the water/vinegar solution makes carbon dioxide gas bubbles. Look closely at the surface of the objects added to the bubbly solution. The surfaces will have tiny gas bubbles that will grow larger until they are big enough to float the object up to the top of the liquid. When the object reaches the top, some of the bubbles will burst. The object is then too heavy for the remaining bubbles to hold it up. The object then sinks to the bottom, where more gas bubbles stick to it and grow larger, an the cycle is repeated.
A drop or two of food colouring in the solution makes a nice display. Two or more jars with dancing raisins or mothballs, in the colours of the season, make a nice display that will often last for a day or two before either the baking soda or the vinegar needs to be replenished.
Other Variables to Try: (What Will Happen If I ...)
Small buttons should also act the same as the raisins, peanuts, etc. Carbonated soft drinks will provide the same action as the water/vinegar solution. Again, CAUTION should be exercised if mothballs (toxic!) are used, to prevent young children from mistaking them for candy. Just to be safe, DO NOT eat or drink ANY of the materials used for this experiment!
Bubble Ballet (Parent/Teacher Page):
Applications to the Alberta Science Curriculum:
Grade 1: This activity can be used as part of the "Creating Colour" Unit, if the food colouring is used. Children love mixing colours drop by drop and seeing how they diffuse throughout the solution and mix together, creating new colours.
Grade 2: Applicable to the "Exploring Liquids" and the "Buoyancy and Boats" Units. It becomes evident that if an object has more gas bubbles on it, it is more likely to float. The density of the object changes, depending on the amount of gas bubbles attached to it.
Grade 5: For the "Classroom Chemistry" Unit, we have taken some common household materials and done something uncommon with them. This is a new demonstration of use for the usual "baking soda volcano" materials. All of the three states of matter are demonstrated in one container. Solid (peanuts), liquid (water/vinegar solution) and gas (carbon dioxide bubbles) are all present.
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