Determining the empirical formula of a compound is a classic chemistry experiment. Yet there are few reactions that can be done in a relatively short time frame, without many procedural steps, and interfering side reactions. The reaction of magnesium and oxygen has been historically a very popular lab to determine the empirical formula in first year chemistry classes all over the world. Yet it is fraught with complications. The most obvious one being that air is mostly made up of nitrogen, so you don’t get pure magnesium oxide, but a mixture of that plus magnesium nitride.
Although it is certainly important for students to recognize the many factors that affect laboratory results, sometimes these factors confuse students and obscure the educational principle of the activity. This is especially true for beginning students.
ZIP-Labs are designed to be completed within a 60 minute time frame but can be expanded to fit into greater time frames as well. This is usually achieved by reducing the amounts of chemicals used, number of steps involved, and the amount of time devoted to each step. The focus of the lab is on the overall scientific principle and less on accuracy/precision. Students are asked to record data as accurately as possible given the time allowed, but they are given sample data that will yield good results. Students are asked to compare their results to the idealized results. They are then asked to think about how the limitations and simplifications affected their results in hindsight.
I realize this is not a perfect solution and I’m not recommending that all labs be conducted this way, but I do feel sometimes student can’t see the forest through trees when the laboratory procedures are too complex or there just isn’t enough time to complete the lab and obtain meaningful results.
During ZIP-Labs, I ask students to focus on one or two chemical principles and/or skills. I find that students are often more apt to understand the sources of error, ways they could perfect their results, and the overall chemical principles as a result.
Each Zip Lab includes potentially much more than any teacher will use at the particular grade level he or she may teach. However, it is my hope that teachers, and students, at lower grade levels will gain valuable insight by looking ahead to see how their teaching/learning will be applied in the future. While teachers and students at higher grade levels can reflect on topics that they should have learned in earlier grades. It is my hope that students see their education as a continuum rather than a series of disconnected and random topics.
Zip Labs include diagrams and illustrations that I hope are appealing to a wide range of ages. However, teachers can choose to omit them if they like. Also included is a Common Core ‘Depth of Knowledge’ and grade level range ‘sliding’ indicator to help students visualize the relevance of their work.
Empirical Formula: What you get…
Activity cover sheet
Results and conclusions worksheet
Advanced practice problems
-Depth of Knowledge & Grade Level Slide Indicator Graphics
This unit activity meets or exceeds 21st Century and STEM learning expectations, and Common Core learning outcomes. Note: although ZIP-labs fulfill many CCSS specific CCS standards are not listed because ZIP-labs are designed to be used over many graded levels so the specific CCSS may be different depending upon these factors. For a list of CCSS in your state please visit- www.corestandards.org
Working to change STEM to STEAM.