Wednesday, March 5, 2014

Experiments We Love

Last weeks tips for young scientists seemed to be a popular post, so I thought I would write out directions for a few of the experiments we enjoy. I picked things that need none to minimal special equipment, most of which can be found at your local grocery store.

 Color Changing Volcano 

This was his favorite experiment from 3 til very recently. It is really great for little kids who are
still exploring what color mixing will do, not to mention it makes a big mess so how can you go wrong :)
  1. Put water and baking soda in one container, add baking soda until no more will mix in with the water. 
  2. Put white vinegar into another container
  3. Add different primary colors to each container. I've done it before with lots of test tubes so that he had lots to test. 
  4. Depending on age/ability of your child, give them the test tubes and let them pour into an empty container or simply have them observe as you pour things together.
  5. To mix it up: They can measure out different amounts of the vinegar/baking soda. What ratio gets the best explosion? 50/50, more vinegar, more baking soda? What happens when you mix all 3 primary colors? Can you get different shades of purple/orange/green by adding different amounts of red/yellow/blue? 
How it works: Vinegar is an acid and baking soda is a base, when you put acids and bases together you get what is called a neutralization reaction: Acid + Base --> Water + Salt. In this case, carbon dioxide is a byproduct of the neutralization reaction which makes the bubbling.

Pineapple Enzyme Exploration 

Pineapple, like all living things, is full of enzymes. Enzymes catalyze the reactions inside a cell, they make things go faster and cost less energy! Because enzymes do things, you can actually see the results of their work.
  1. You need fresh pineapple, canned pineapple and 3 premade Jell-O cups. 
  2. Cut the fresh pineapple into small cubes. 
  3. Open the 3 Jell-O cups, leave one with out any pineapple (control). Add the freshly cut pineapple to another cup and to the last cup add the canned pineapple. Observe the Jell-O.
  4. This takes a while, after about an hour you can see a difference but after several hours it becomes very apparent. A good time to do this is before school, then when they get home the kids can rush to see the results.
  5. Another variation is to make Jell-O and put 1/3 in the fridge without pineapple, 1/3 with fresh pineapple and 1/3 with canned pineapple and see which ones solidify. 
  6. To make this into more of an experimental setting versus a demonstration setting: ditch the canned pineapple and let the kids treat the fresh pineapple with various things to see what will de-activate the enzymes. Some examples: Microwave at various lengths, freeze it, treat it with chemicals, like bleach (base) or vinegar (acid) that change the pH. 
How it works:  Pineapple has bromelain which are protease enzymes. Protease are enzymes that break down protein. Jell-O is collagen, a protein. When you combine bromelain with collagen, the result is broken down proteins. Lots of different factors can impact enzyme activity, but temperature and pH are two big ones. When they can pineapple they Pasteurize it. AKA heat it until all the potential disease causing critters are dead. The fact that fresh pineapple can "melt" the Jell-O and canned pineapple cannot is because not only does heat kill bacteria, it can also denature (or break) enzymes.

Goop or Ball

This does require Borax, which is a laundry booster/cleaner and can usually be found in the stores though it may take some searching. Borax is the only part of this that you probably do not already have laying around the house.
  1. Gather the materials: Glue (we use cheap white school glue), Saturated Borax (put warm water into a bottle and add Borax until it refuses to dissolve, that's saturated), Water, Plastic bowl, Stir stick, graduated cylinder/measuring cups, and if you want your goop to be colored, food coloring.
  2. Measure out equal parts glue and water and stir together (we do 50ml). 
  3. Add food coloring and stir, if you want colored goop. 
  4. Add Borax solution (30% of combined glue/water mixture, we use 30ml). Stir and you should immediately notice the chemical change occurring.
  5. Play with your goop! It should be sticky and stretchy
  6. To make a bouncy ball, you need to add less water to the glue mixture so that it becomes thicker. This is messy, but fun, you have to pick up the mixture and work it in your hands to become the ball shape. 
  7. Have the kids experiment with different proportions of water/glue/borax to see how the changes impact the reaction. 
How it works: Borax when dissolved releases a borate ion. This ion interacts with the polymer (polyvinyl acetate) in the glue, making a polymer-borate-polymer bridge and forming an even more complex polymer with greater structure than the glue.

What Keeps me the Warmest? 

The idea of insulation is one that us as adults are familiar with, we either praise or curse the insulation in our houses, we like can koozy's when tailgating, travel cups for coffee, etc. But not everyone thinks about the fact that coats/sweaters/etc. are insulating our body from the winter weather. They serve the purpose of keeping heat inside our bodies, not letting it escape into the environment. And there is a fairly simple way to let kids investigate this, though it REQUIRES adult help due to the use of boiling water! You will need a thermometer (we used a digital meat thermometer), jars/glasses that can handle boiling water, boiling water, a timer, and several articles of clothing to test.
  1. Boil water (ADULTS) and measure the temperature. 
  2. Pour water into the jars and close lids if there are any (ADULTS). 
  3.  Put clothing articles over the jars. For his K science project, we did his coat, his hat, a sweatshirt, and nothing (control). 
  4. Wait a specified amount of time. 
  5. Measure the new temperature in each jar and compare it to the first (adults should monitor this as the water inside the jars will still be hot). Which stayed the warmest and thus had the best insulation? 
  6. This is a really versatile experiment because you can test a lot of things, from packing material to clothing. You could run a time course, take the temperature every X minutes for Y time.
How it works: The second law of thermodynamics  tells us that energy only flows from hot to cold objects and the heat will continue to flow until equilibrium (equal temperature) is reached. The articles you place between the hot water and the cold air act as a barrier to the heat transfer and slow the process down. The better insulator the object is, the longer it will retain its heat.

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