laboratory instruction

Silver Plated Bulbs

I have used several different versions of the Silver Mirror or Tollen's Test lab. I am sharing the method that has proven to be the most reliable for me. The solutions should be made fresh, the directions must be followed closely and timing is very important. I like the fact that relatively small amounts of the chemicals are required, but as always you must be vigilant with safety precautions. 

The Dry-Ice-in-Water Cloud

Have you ever wondered where the cloud comes from when dry ice is placed in water? If you think the answer is “atmospheric water vapor”, be sure to read this post because experimental evidence suggests that this explanation is wrong.

A nice quick and easy stoichiometry lab...

Students are told that they have to determine the amount of active ingredient in an antacid tablet. Then I ask them if they have any questions. First it starts with blank stares...then slowly the questions start coming. What exactly is the active ingredient? What does it react with? They are provided information that the active ingredient is baking soda.

ACS publishes Guidelines for Secondary School Laboratory Safety

The ACS Committee on Chemical Safety has published new Guidelines for Chemical Laboratory Safety in Secondary Schools. This document is organized with the R.A.M.P. concept – Recognize the hazard, Assess the risk of the hazard, Minimize the risk of the hazard, and Prepare for emergencies. The online document includes two pages for each letter that could be printed and posted in the classroom to reinforce these principles of safety. The documents are provided to strengthen the safety practices of teachers and help them to promote a culture of safety that their students will take with them throughout their academic and professional careers.

Hydrate Labs, Microscale Chemistry and Cage Fighting....

For years my students would heat the hydrates in glassware, burn themselves, break the glassware and splatter salts and thus their data, all over the lab bench. A few years ago Bob Worley came up with a great microscale technique. Essentially, it takes a used bottle cap without the plastic and this is used as the dish. Next, there is about a three inch machine screw that goes through a drilled hole in the cap. A nut is placed on the screw to hold everything in place and cheap pliers are used to hold the entire assembly over the flame.

Equilibrium Lab

Just this week I'm reviewing equilibrium with my IB Chemistry seniors after they finished some summer study on the topic. One of our classes was spent manipulating a classic equilibrium involving copper ions and a copper-chloride complex ion.