Friday, May 20, 2011

Kitchen Chemistry!

A lesson in Acids, Bases, Ph, and SLIME....

Keeping things fun and interesting in my house often relies on the sacrifice of cleanliness and order. Personally, I think this is a great way to live life. However, if you wish to keep slime, liquids, and Ph testers off of your counters and floors, you may want to consider laying some newspaper down, because things are about to get really messy!

A LESSON IN ACIDS, BASES, and PH 

We began our school day with a discussion on acids and bases. Most liquids have either basic or acidic traits, and many of the liquids we are exposed to on a daily basis are geared toward Ph neutral (around Ph7). If you need a refresher on what acids and bases are:

ACIDS: corrode metal, taste sour, change litmus tests to red, and become less acidic when mixed with bases. Examples of Acids: Lemon Juice, Orange Juice, Vinegar, Stomach Acid

BASES: Feel slippery, change litmus tests to blue, and become less basic when mixed with acids. Examples of Bases: Baking Soda, Blood, Egg Whites

In discussing this with my daughter, I made sure to talk a bit about citric acid first. She loves to eat oranges, so using them as an example was much better than talking about more abstract examples. We then talked about how acid "eats things", and recalled our earlier conversation on what oxygen does with iron. We walked outside and looked for some rusted iron, this demonstrated what "corroding metals" meant. Find an example that your child will identify easily with and go with that. 

Now, on to the PH Scale:



We looked this over a few times, and even drew out a copy of our own to make sure that we understood it really well. We talked about various liquids, soils, and pool chemistry, and looked at where they might fall on the Ph scale. If Habanero peppers like soil with a Ph of 6.5, does that make the soil more acidic, or basic? If our pool needs to have a Ph of 7.6, is that acid, basic, or neutral? If something has a Ph of 14, is it safe? No! What about if it has a Ph of 0? No, it might eat your skin off! If you shout these last two out with your kids, it makes this part quite enjoyable.

Now that we've gone over acids, bases, and Ph, it's time to head to the kitchen for some real life examples. What can we find in our kitchen to test? How many of our household liquids (that are safe to play with) are acidic or basic? Will they all be neutral? Let's find out.

For this demonstration, you will need the following: 

1. A way to test PH. I monitor the chemistry of the pool in our backyard, so I had an old Ph test kit on hand. You can buy litmus paper online, it's fairly inexpensive (this place sells it for $1.95). You may even be able to find it at a local pharmacy, but you might want to call them first.


Our first test of orange juice in an old pool test kit.

2. Liquids to test. We tested vinegar, orange juice, water, and hydrogen peroxide.


This was our test of water. The color of the dye will begin to change immediately upon  contact.

Now let your child at the Ph testing kit! My daughter had a great time using our transfer tubes to put the liquids in our test kit, and dropping the litmus liquid into the container to see what color the liquids would turn. Most of them were very acidic, with water being the exception, which was closer to neutral. 

To further an understanding of how acids and bases interact with each other, try the following:

1. Get 1/2 cup of milk.
2. Add 1/4 cup of vinegar.
3. Microwave for 20 seconds.
4. Pour through strainer.

What you will find is that the acidic vinegar has quickly interacted with the basic milk. It has made the milk far more acidic, and has curdled it. Feel free to dump it down the drain now, curdled milk is pretty disgusting. Besides, we're almost ready for the grand finale....

OOZING GLOOPY SLIME!!!

Who says slime can't be pink?
There are many ways to make slime, but only a few of them have stood up to the test of sliminess and durability. Here are two recipes for slime, courtesy of our friend Science Bob.

Recipe for liquid cornstarch method (pictured above):

Materials Needed:
1.
1/4 cup water 
2. 1/4 cup glue (Elmers or equivalent)
3. 1/4 cup liquid starch (you can find this near the spray starches in the laundry aisle)
4. Food Coloring
5. Mixing bowl

Instructions:

1. Put your glue into the mixing bowl. Some of it will stick to the cup, try to get as much as you can out of it. The more glue you have, the stickier your slime will be.

2. Add your water and mix the two together. Let your child pick out the color he/she wants to use, and let your child mix it in while you add the liquid starch. Your child will notice that the mixture is getting a little more difficult to stir.

You have about 5 seconds to double check to see if your counters are covered (if you care about such things) before your child will begin to pull the gloopy stringy mess out of the bowl and play with it. This stuff is as messy as it is fun, but it cleans up very easily.

Recipe for Borax method:

Materials Needed:

1. 2 disposable cups
2. spoon (for stirring)
3. Tablespoon
4. Food Coloring
5. 3 tbsp water
6. approx 1/4 cup of glue
7. Borax (powder form, can be found in the laundry aisle with the detergents)

Instructions:

1. Take one of your plastic cups and fill it with water. Add a spoonful Borax, stir, and set aside.

2. Take the other cup and add 1/4 cup (about one inch) of glue. Add 3 Tbsp of water and stir. Give the cup to your child, and let him/her add the food coloring.

3. While your child is stirring, get 1 Tbsp of the Borax solution you prepared earlier, and add it to the cup. Again, you have five seconds as this goop solidifies quite a bit before your child starts taking it out and playing with it! Here is what you will end up with:


Now THAT's some hardcore slime!

So now you've had quite a busy day of chemistry experiments! If you're still up for some more, let your child sprinkle some baking soda over your counter. Then let your child pour (slowly!) some vinegar over the baking soda. He/she will have a great time with this chemical reaction, and you can get your child to help you clean your counter without it seeming like a chore!





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