Science for Kids: Chromatography and Precipitates

I love when I get a chance to show off science at a school or organization.  When it comes to finding these engaging activities the internet can always be a great source of inspiration.  But as often happens I rely on the awesome people I work with for ideas and activities.    I can't even put into words how working with such inspiring colleagues makes STEM outreach so fun and exciting.

I say all of this because I was invited to go by Davis Drive Middle School in Cary, NC to work with a chemistry club.   I was looking for a new activity since these kids had already seen most of the activities I had in the toolbox.   I was talking to two people I work with and just like that we had two projects ready to go.

Home Chromatography

The first thanks for this activity goes to Marie.   Marie has developed a great exercise to teach chromatography while also introducing some basic practice in pipetting.

The kids received a basic intro into chromatography.

Before the we actually did the chromatography exercise the kids needed to know how to pipette only 3 ul onto the chromatography filter paper.   So we had some food coloring and pipettes for everyone to practice using a pipette.

Here were the pipettes they got to practice with.

In groups they practiced setting the pipettes to the right aliquot setting and pipette food coloring on a practice sheet.  The sheets they were practicing with looked like this:

And the practice in action:

After had pipetting down, we moved on to doing the chromatography exercise.  Each group had blue, yellow, and red food coloring and the then two tubes of a mix of colors (mystery tubes).  There task was to see what colors were in the mystery tubes using chromatography. 

In this exercise, salt water (mobile phase) would move the food coloring up through the filter paper  (stationary phase) and the colors would separate. 

Here the kids got super excited to see the filter papers get added to the salt water.

The results were beautiful!

The summary of all the above exercises are:

Precipitates


After we finished the pipetting activity,  Jun talked about precipitates.  When you mix two chemicals sometimes a precipitate will form.  Jun worked out a simple experiment for the students to try it out.

We mixed Calcium Chloride with Baking Soda.  This causes a reaction in which salt, carbon dioxide, and water are formed as well as calcium carbonate.  Calcium carbonate is basically chalk.   So once the mixture was mixed there were bubbles forming which was the carbon dioxide and a lot of white stuff which is the calcium carbonate.

Here is the procedure as well as the reaction.

Thanks Davis Drive for having us!