Steaming with STEM: Let it Snow
Let it Snow, Let it Snow, Let it Snow!
If you live where there is snow, it can be fun to play in it for a while—but it can get quite chilly! Or maybe you live in a place that does not get snow. Wherever you live, you can engineer snow in your own kitchen.
Materials Design Challenge: Another winter and no snow. People in your community are asking for a little snow this year. The City Council has hired you to make some snow, so that people can go sledding and enjoy a Winter Wonderland.
Two large plastic or glass containers
Measuring cup
Baking soda
Measuring spoons: a teaspoon and a tablespoon
Sticky note
Pen or pencil
Dishwashing soap
Vinegar
Small waterproof items to decorate your creation (optional)
Directions
- Scoop one cup of baking soda into the container without the sticky note. Add three tablespoons of water and mix the ingredients
together to make a dough. It should feel like modeling clay. You can add water in small amounts at a time if the dough is too crumbly, until you reach the right consistency. - Have fun molding a snowman, a polar bear, or any other critter. Feel free to decorate your creation with water proof objects. Keep your creation in that container. Does the dough stick well together? How does it feel?
- Now, take the container with the sticky note reading “Soap,” and make a second teaspoon of dishwashing soap to the container, followed by three tablespoons of water. Do you notice the difference in the recipes?
- Mix the ingredients together to make a dough. You can add water Now, take the container with the sticky note reading “Soap,” and
make a second teaspoon of dishwashing soap to the container, followed by three tablespoons of water. Do you notice the difference in the recipes? In small amounts at a time until the dough molds well. - Have fun molding a second critter; it could be very similar or quite different from your first creation, but try to make something of similar height and size. Feel free to decorate this creation with waterproof items. Keep your creation in that container. Does this dough feel similar or different compared to the other one? Admire your creations. In the next step, you will melt them by pouring vinegar over your creations (but do not do it yet)!
- Can you predict what will happen? Remember that the main ingredient of your dough is baking soda. Have you ever mixed baking soda with vinegar before? What happened? Would something similar happen now?
- Fill your measuring cup with vinegar and pour all of it at once over your first creation. What happens? What do you see and hear? Is it as you expected, or is it different?
- Fill your measuring cup again with vinegar and pour all the vinegar at once over the other creation. What happens this time? What do you see and hear? What is similar and what is different between the two containers? Do you remember what was different between the two recipes? Would that explain the difference between the observations?
- Most likely, your critter is partly destroyed and only partially standing. Try something different this time; find out what
happens when you pour water over your critters. What do you think will happen? - Rinse your measuring cup and fill it with water. Pour all of it at once over whatever is left of your first creation. What happens? Is pouring water over it as exciting as pouring vinegar over it?
- Fill the measuring cup again with water. In a minute, you will pour it over what is left of your second creation. Can you predict what will happen if you pour it, all at once, over whatever is left of your second creation?
- Go ahead. Was your prediction, right?
- If your creation is partially standing, keep trying out different actions. What happens if you pour slowly? Take some dough in your hand and pour vinegar or water over it as you hold it over the container. How does it feel?
Cleanup
Pour your liquid solutions down the drain. Any solid dough can be thrown in the trash.
What Happened?
Did both creations fizz as soon as vinegar touched them? When vinegar comes in contact with baking soda, the two chemicals react with each other. The result is a gas bubbling up in a watery solution. The bubbles create the fizz and sizzling sound.
Whatever was left of your first creation (the one without the soap) was probably standing in a pool of a bubbling watery solution, where bubbles burst open as they reached the liquid surface. This was probably different for your other container.
The left overs of the second creation—which had dishwashing soap mixed into the dough—were probably surrounded by a layer of white foam. Chemicals in detergent allow soapy solutions to spread out. The bubbles created in the chemical reaction still rose to the surface, but now, the soapy solution trapped the bubbles, forming a foam. As water does not react with baking soda, pouring water over your creations probably just washed away some dough without any sizzling, fizzing, or foaming.
Digging Deeper
Just a few common and safe household chemicals—baking soda, vinegar, and dishwashing soap—can lead to an interesting project that examines two areas of chemistry. Vinegar (or diluted acetic acid) combined with baking soda (also called sodium bicarbonate) yields a cascade of two chemical reactions. The end products are carbon dioxide (CO2, the gas we breathe out) and water, in which two chemical products(sodium ions and acetate ions) are dissolved. As you observe this reaction, you see the carbon dioxide gas as bubbles rising to the surface of the liquid and hear a fizzing noise. Other acids, such as those in lemon juice, can also be used to make the dough fizz. Neutral solutions (such as water) or base solutions (such as milk) will not cause a chemical reaction. Neither creation will start fizzing when these are poured over them.