Wednesday, August 28, 2013

Conservation of Matter: Steel Wool & Vinegar

This is another versatile demonstration to use in your student of chemistry - learn about chemical changes, chemical reactions, conservation of matter and even air pressure.

Depending upon the take-home message you want your students to get, you might structure the activity in a few different ways, but the basics are the same.

You'll need some steel wool, vinegar, bottles or flasks and a balloon.

Pull apart some strands of steel wool and push some into each bottle.  Pour some vinegar onto the steel wool.  (Some instructions tell you to soak the steel wool in the vinegar for a few minutes and then remove the steel wool.  I just left mine in it).

Stretch a balloon over the opening of one bottle, but leave the other as is.

You could find the mass of each system at this point, if you're interested in conservation of matter.

Allow the bottles to sit and the reaction to occur. 

The vinegar removes the coating from the steel wool, and the steel will be begin to oxidize in the presence of oxygen. 

As the reaction is occurring, the balloon will be pushed into the bottle.  Why?

The oxidation reaction is using up the oxygen in the bottle, which will lesson the number of air molecules in the bottle, thus reducing the pressure in the bottle.  Because the pressure outside the bottle is greater than the pressure inside the bottle, it will push the balloon in. 

You can stop there if you're interested in simply looking for evidence of a chemical change, studying the chemical reaction or seeing the affects of air pressure. 

If you're interested in conservation of matter, continue on. 

Find the mass of each system once again.

The closed system (i.e. the one with the balloon covering the opening), should have the same mass it had in the beginning. 

The open system's mass should have gained mass, as it continued to pull more oxygen into the system to carry out the reaction further. 

Wednesday, August 14, 2013

Oceanic Acidification & Seashells

Birds and their eggs aren't the only animals for whom an increasingly acidic environment would cause great harm.  This simple activity demonstrates the effect of acid on shellfish.

You'll need a couple of shells (large or small, any variety, but for the sake of comparison, it's good to have two of the same), two cups or beakers, vinegar and water.

Place each shell in a cup/beaker.

Cover one shell with water.  You might want to use salt water, as these organisms live in the ocean, but I didn't think of that as I was setting things up. You could also do three shells at a time - one in vinegar, one in water and one in salt water.

Cover the other shell with vinegar. 

You'll notice that the shell in the vinegar immediately begins to form bubbles and fizz.  The vinegar is breaking down the calcium carbonate that composes the shell. 

Within 24 hours, you'll notice the shell that was in vinegar has holes in it.  If there was still a creature living in the shell, this could obviously be detrimental.

Vinegar, while a weak acid, is quite a bit stronger than acidified ocean water.  The stronger acid speeds up the process, making it visible within a short period of time - perfect for students to grasp an understanding of the process.  Shells in an acid ocean environment would be subject to the same chemistry, it would just take place at a slower rate.  

You can learn more about the chemistry taking place, as well as ocean acidification here.  

You may wish to continue to leave the shell in the vinegar for an extended time to observe further.  If so, it may be necessary to replace or replenish the vinegar.  (I used a small enough amount of vinegar that the chemical reaction came to a halt within a day or so).


Remember to head over to Pow! Science! to check out their merchandise and put your Science Matters discount to use!  Details can be found here.  

Wednesday, August 7, 2013

Cookie Fossil Dig

Can your students work with the precision and patience needed by a paleontologist on a fossil dig?

Provide each student with a chocolate chip cookie, a toothpick and a small paintbrush.  See who can remove the most unscathed chocolate chips without breaking the cookie!

You might want to have your students try a few different types of cookies - are the chips easier to remove from crisp cookies or soft, chewy cookies?

I did this simple, paleontologist cookie dig with students at our library during a summer program, which was perfect for the age group I was working with (3 - 10).  However, I've also done cookie mining with middle school students.  Women in Mining provides a fantastic activity that includes a financial aspect (students are given a budget and have to purchase their cookie, mining tools, mining time and reclamation costs) in addition to precision.  I've mentioned it before, but it's worth repeating... take some time to check out the other activities on the Women in Mining website - they're really well done!

Tuesday, August 6, 2013

New School Supplies and Pow! Science!

I don't know about you, but one of my favorite parts of a new school year, in addition to a fresh start full of possibility, is all of the new "stuff" that goes with it.  Brand new pencils and pens.  Fresh notebooks that don't have a mark in them (unless one of my children has gotten to it before me....).  Perfectly clean glassware.  Replacement supplies for your favorite demonstrations and labs.  Science "toys" that you know are going to capture your students' interest.

Seriously.  Does anyone have any more fun spending their classroom budget than science teachers?  Maybe art teachers.... Maybe. 

I've got a fairly-new-to-me source for some fun and educational science supplies: Pow! Science! (Great name, right?)

Their prices on glassware (beakers and graduated cylinders) are very competitive.  (It's even better when you add on a Science Matters discount.  That's right!  Read on, my friends). And it's real glass!  I really dislike plastic beakers.  It's okay for graduated cylinders, but real glass is still so much better.  The selection and quantities are limited, so it's likely not the place to go if you're looking to outfit a whole science department.  But, if you're looking for some real glassware to use in your home laboratory or a few pieces to add to your individual classroom, I highly recommend you take a look. 

Some other "basic" supplies you might be interested in:
Litmus and pH Paper
Eye Droppers
Magnifying Glasses

And then there's the stuff that's a little more fun...

Now for that discount...
Pow! Science! is offering Science Matters readers a 15% discount on their entire purchase!through September 30.  Simply use the code SCIMATTER0913 when checking out.  There's no minimum purchase required and you can use the code as many times as you like.  
So, shop and shop often! 
Kick off that new school year in style!  Or if you're all set for the school year, why not get a jump on some holiday shopping for the scientists in your life.... :)
One more thing... if you live near or happen to be visiting the Rhode Island vicinity, you can visit their brick and mortar store.  Also, check out their programming: free Lego days, birthday parties, homeschool and scout presentations and so on.