Crystals are Cool: Making Rock Candy

Wish I Had Noted the Name
Creative Commons License photo credit: biggertree

There are so many different kinds of crystals all around us, but just what are they anyway?

Put simply, a crystal is a grouping of molecules or atoms that is organized in a specific way.  Every crystal has a unique shape and properties that make it recognizable.  In today’s experiment, we will be working with sugar crystals which are oblong and slanted on the ends.

There are a couple of things going on that contribute to the growth of sugar crystals in this experiment.  First, you will be creating a supersaturated solution by heating a saturated sugar solution and allowing it to cool.

Supersaturated solutions are solutions that are so full (of sugar in this case), that they are unstable.  The solution you will create will contain more sugar (the solute) than it can hold in a liquid form.  Therefore, the sugar must come out of solution – forming what is called a precipitate (also known as yummy rock candy).  The second mechanism that helps to form the sugar crystals is evaporation.  Slowly, the water evaporates from your solution.  As this happens the solution becomes even more saturated with sugar and the sugar will continue to come out of the solution and form sugar crystals.

Blue Sugar
Creative Commons License photo credit: karsten.planz

What you are left with is a delicious science treat!  Make sure to only eat a little at a time and keep the rest sealed in a baggie.  Also, don’t forget to brush your teeth; it is pure sugar after all!  Have fun in your kitchen lab and don’t forget to be safe!  Always include an adult when trying new experiments.

Grab a handy adult; you will need one to do this activity!

Materials:
Granulated sugar – 1 cup
Water – ½ cup
Saucepan
Food coloring
Two canning jars
Spoon

What to do:
1. Dump one cup of sugar and ½ cup of water into your saucepan.  Don’t stir it!
2. Find your adult and have them help you put it onto the stove over medium-high heat.  Wait for the mixture to come to a boil and let it boil for one minute without stirring.  If you want colored rock candy, you may add some food coloring while it boils.
3. Instruct your handy adult to pour this mixture into the two canning jars.
4. Find a place on your counter that you can let the two jars sit undisturbed for two weeks.
5. Observe them once a day.  Slowly, crystals begin to form.  When you see a crust form on top of the jars, use a spoon to carefully break the crust so the water can continue to evaporate.  Don’t do anything else to your jars other than this!
6. When you feel like you have enough crystals of the right size, have an adult help you remove them from the jar using a dull table knife.
7. Eat and enjoy!  Don’t forget to brush your teeth, it is sugar after all!

The Science of Food: Emulsions on your Salad!

Emulsion Repulsion: Science on your Salad!

A simple way to explain an emulsion is as a suspension of two liquids within each other that normally would not mix (like oil and water).  Picture a cup with vinegar.  If you pour oil into the vinegar, the oil will float on top of the vinegar because it is less dense.  What happens if you briskly whisk them together?  Well, the liquids start to mix together and tiny droplets of each liquid become suspended within each other.  When they are uniformly dispersed in each other (evenly mixed) then you have an emulsion.

A simple mixture of oil and vinegar will ultimately separate back into vinegar and oil because at a molecular level, there is nothing holding the two kinds of liquids together. This temporary emulsion just happens because of the whisking. To get a permanent emulsion of these two liquids you need a third ingredient to hold the two immiscible (non-mixing) agents together and prevent them from separating.  This ingredient is called an emulsifying agent.  This agent is like a mutual friend who likes both the oil and the vinegar and holds them together.  It creates a weak chemical bond with each liquid and becomes like a bridge between them.  Eggs are a very common emulsifying agent as is mayonnaise and hollandaise sauce.

Now that you understand emulsions, go into your kitchen and make your own!

egg-whisk-2
 Creative Commons License photo credit: LDCross

Materials:
Measuring cup
Measuring spoons
Vegetable oil
Vinegar
2 Mixing bowls
Whisk or hand egg beater
1 Egg

Procedure:

Part 1
1. First grab an adult to help you.  Also, we will be using a raw egg, so this experiment is not for eating, it’s just for experimenting!
2. In a mixing bowl, place ½ cup of vegetable oil.
3. Add one teaspoon of vinegar and use a spoon to gently mix them together.  Observe what happens.
4. Now, use the whisk or a hand eggbeater to mix the vinegar and oil.  What happens now? 
5. Watch the mixture for a few more minutes.  Observe what happens.  They should begin to separate.  Oil and vinegar do not stay well mixed.

Part 2
1. In a separate bowl, add one teaspoon of vinegar and an egg yolk (you will need to separate it from the egg white first).  Mix these two ingredients together well.
2. Now, add one cup of oil and two teaspoons of vinegar.  Mix the egg mixture together using the whisk or eggbeater.  What happens?  Observe.
3. Discuss your results. 

Emulsions aren’t just an experiment, though – they’re something you can see everyday. In honor of Big Bite Nite tomorrow night, Chef Sandor Edmonson from *17 at the Alden and I whip up a tasty vinaigrette. Click the video below to see the dish in progress as we create great example of an emulsion.

Want to learn how to make more food at home?
Learn the ingredients for ice cream.
Learn how to make your own butter.

Want to see more in the Science of Food video series?
Watch me make ice cream with Quattro’s Executive Pastry Chef Philippe Valladares.
See me make butterwith Adam Puskorius, Executive Chef at Polo’s Signature.


High Fashion: Hot Wax Batik

Recently, teachers had a great time at the Museum participating in fun fashion projects during our ExxonMobil Teacher Training called High Fashion.  Try out this activity from the class.  Have fun and be careful! 

Hot Wax Batik

a woman's work...
Creative Commons License photo credit: filtran

Materials:
Adult helper
Soap kettle
Paraffin wax
Iron – be careful to protect it from wax or use an old iron
Q-tips
Thick brown paper – like grocery bags
Cold water dye
Plain cotton fabric
Scratch paper
Pencil
Old newspaper

 

Procedure:
1. Grab an adult to help you.  You must have supervision for this project!

2. What is batik?  Batik (pronounced ‘Bah-Teak’) is a technique used to dye fabrics. Wax is applied to the areas on a piece of fabric that are not to be dyed.  There are various ways that this is accomplished, but the most common are for the hot wax to be “painted” onto the fabric using a brush or to be poured onto the fabric directly.  Once the wax hardens, it has penetrated the fabric and it is now time to dye the fabric.  The hard wax prevents the dye from penetrating the fabric in the areas it has been applied.  The wax is removed after the dyeing process by using a solvent or heat. 

3. Pick a fabric that you would like to dye.  Thin cottons work well (not t-shirt cotton).  You can buy remnants cheaply at a fabric store.  You will need to make sure and wash the fabric before the activity for the dye to penetrate properly. 

4. Melt the wax in a soap kettle or in the microwave.  Please be careful, as hot wax can cause serious burns. 

5. Mix the cold water dye according to package directions.  Be careful not to get this on your clothing as it will NOT come out.  Put the dye aside for now.

Sarah's Eyes
Creative Commons License photo credit: allyrose18

6. Sketch out your design on a piece of scratch paper.  Make sure to keep in mind the size of your fabric and plan accordingly. 

7. Put down some old newspaper to work on.  Dip a q-tip into the wax and use it to draw the design on your bag.  You could also use a fine-tipped paint brush to apply your design.  Allow the wax to dry.  This takes very little time.

8. Put on disposable gloves and immerse the fabric into the dye.  Be careful not to get it on your clothes, as it will stain permanently! 

9. Remove the fabric from the dye and allow it to dry.

10. Using an iron, remove the wax by pressing the fabric between two pieces of heavy brown paper.  Grocery bags work well for this.  It is best to use an old iron or extra paper to protect your iron from the wax.

11. Look!  You have a beautiful fabric design!

12. Do not wash your fabric with other clothing as some of the dye may come off in the wash.

Sharky-Locks and the Three Gummi Bears

Need another excuse to buy candy this October?  Like cheap entertainment? Of course you do! How about some do-it-yourself grow-animals? For a buck or two, you can have a hundred edible expanding critters of your very own.

You need a few gummi bears or other gummi snacks (I grant you they are of questionable nutritional value, but they have their uses) and water. That’s pretty much it — see what we mean about cheap? 

I started with three gummi bears and one much larger gummi shark which had a disturbing layer of opaque white gummi on the bottom. 

If you want to know how much your gummi critters grow, you might want to trace around them or measure them, or just set some of your gummy snacks aside for comparison later. I had an electronic balance handy, so I used it, but that’s definitely not necessary:


The growing:  You need a container that can hold your gummi animals with a little room for expansion, and enough water to keep them covered:

And now we wait.  You may notice some expansion an hour after you begin, but your animals will look significantly bigger after 12-24 hours in water.  A few things to note: If you plan to eat your critters once they expand, please refrigerate them during the soaking process (this may slow their expansion somewhat, but you will also slow the growth of not-so-delicious bacteria). Whether you are refrigerating or not, set your critters somewhere and leave them alone as much as possible; if they jostle around too much, they may just dissolve and leave you with an unimpressive pool of colored sugar-water.

After a 20-hour soak, one of the bears intimidates his dry brother:


The “after” measurements:

This bear grew about three times as large as it was originally, and the shark about twice as large (it might have expanded further if given more time but it fell apart after being handled.)

Here’s a brief explanationof growing gummi snacks.

Extensions to try:  Soak your critters in distilled water, salt water, soda or juice, or try soaking an expanded critter in salt water.  Do some brands of bears hold up better or expand more?

(In case you were curious: Yes, you can spell it either way: gummi or gummy.)