Potions Class!

My students know that I'm a pretty big geek.  One of my goals as a teacher is to identify and draw out the inner geek in my students.  For an activity that I am doing to review a lot of the chemical reactions concepts we are going to create potions.  I Start by having them read excerpts from Harry Potter.  We then identify the things involved with making a potion that are nearly identical to creating chemical reactions.

Aftwerwards, I have them run through a series of stations that illustrate a different chemical concept.  However, since this is a potions themed lesson, I've renamed all of the chemicals to something a bit more...interesting.

 

Here's a classic vinegar and baking soda experiment.  I've changed the concentrations of the vinegar to show how the reaction rate can be controlled.  Also, the reaction is being done in a closed system (balloon) so that the "spirit" that is released can be captured.

 

Here's a reaction with luminol and hydrogen peroxide that produces light.  I tell them that they're making a firefly lure potion.

These reactants will precipitate silver, which can stick to the inside of a test tube and make it shiny.

For acid/base chemistry, they'll create a potion that can change into ALL OF THE COLORS OF THE RAINBOOOOOOOOW!!! (with a universal indicator)

Finally, they'll produce "fairy flames" from a variety of fairy samples.

Iodine Clock!

This week we are discussing reaction rates.  I had my students mix the reactants for an iodine clock reaction with increasing amounts of water to dilute them.  The result was a series of reactions that were arranged in order of fastest to slowest.  I had all of the students mix at the same time to get an inetersting, domino-like effect.

Cornstarch FIREBALL!

Today we are discussing different ways to increase the rate of a chemical reaction.  The concept of surface area is often difficult to teach to 8th graders.  Whenever I have a difficult concept to teach, I usually resort to lighting something on fire.

Corn starch is a chemically unreactive substance...until it is dispersed into a cloud.  Then it can be ignited into a spectacular fireball.  Below are two clips of me doing just that at 300 and 600 frames per second.

300 FPS

 

 

 

600 FPS

LEGO Chemistry!

Chemistry is an abstract thing.  I do not possess the ability to show students how bonds are broken and reformed in real time.  We have to use models.  A particularly peevish concept to teach is that of conservation of mass.  I've jumped into balancing chemical equations with students and lost most of them immediately.

So...nowadays I bust out the LEGOs.

Before we multiply coefficients and compare reactants with products, we get a sense for how mass is held constant through a chemical reaction.  Students make something out of LEGOs.  They record the mass.  Students combine their construct with another and record the total mass.  Students break their object into several smaller objects and record the mass.

Besides the small differences in measurements (we discuss the to err is to be human idea), the total mass of the objects remains constant.

Now, we can talk about how elements combine to form products knowing that nothing will be created or destroyed.  Just substitute chemical symbols in for bricks.