density

That’s What Scientists Do!

Measurement Challenge

As I began to prepare my labs for this upcoming year, I decided to put a bit of a twist on a previous density of a block lab I had used in the past entitled the Measurement Challenge that is sold by Flinn Scientific. It can also be used to find the mass of a block given the materials density and requiring students to measure and calculate the blocks volume. My added twist resulted in great scientific discourse. 

My First Lab of the Year

measuring volume and mass of water

My first experiment involves measuring the density of water. Each group of two kids is assigned a specific volume of water from 10 to 100 mLs on the tens. They simply measure the mass of an empty graduated cylinder and then add the water and find the mass again. Once they have their data they go around the room and find another group that has one of the volumes that they need and get the data from them and record their names. Once complete they generate a graph of the data and answer a few simple questions. The whole procedure can be completed in about 20 minutes.

Time required: 

10 minutes prep

20 minutes classtime

Chemistry in a Bottle

density bottles

Are you familiar with the dynamic density bottle experiment? This interesting experiment was invented by Lynn Higgins, and is sold by various science supply companies. Two immiscible liquids (usually salt water and isopropyl alcohol) and two different types of plastic pieces are contained within a dynamic density bottle. The plastic pieces display curious floating and sinking behavior when the bottle is shaken. 

Unit Conversions: The good, the bad and the ugly

Crutches

Like most chemistry teachers, one of the first things I go over in the beginning of the year is unit conversions. Students come into my class with all sorts of prior knowledge concerning unit conversions; some good, some bad and some downright ugly.

Chemical Mystery #7: Curious Cans

floating cans

​Q: Does an unopened can of soda pop float or sink in water?

A: It depends!

See if you can figure out what is happening in this twist on the classic floating-and-sinking soda can experiment.

JCE 92.09—September 2015 Issue Highlights

Journal of Chemical Education September 2015 Cover

Effective Student Engagement

The September 2015 issue of the Journal of Chemical Education is now available online to subscribers. This issue includes articles on flipped classroom; introductory and general chemistry; organic chemistry activities; biochemistry demonstrations and labs; computer-based learning; chemical education research; from the archive: chemistry in context.