Erica Jacobsen shares highlights from the November 2019 issue of the Journal of Chemical Education of special interest to our ChemEd X community.
I allowed my students to choose between two separation type laboratories. About two thirds of the class chose to separate the flavoring out of a grape of cherry soda. The rest of the students used paper chromatography to determine if red-40 dye was in a specific type of candy.
The first chapter of every middle and high school science textbook I have ever seen contains an oversimplified section on “the scientific method.” I wanted my students to gain an understanding of science by doing science, as best as we can replicate in a classroom, though inquiry labs, class discussions, and defending claims with evidence.
I think this experiment provides a fantastic vehicle to involve students of all ages in small, hands-on and exploratory research projects. Like many others, my students and I have investigated various aspects of this interesting fountain.
To assist in grading the lab results for this and other quantitative labs that we did, I created Excel spreadsheets where the students’ results could be entered. The spreadsheet then did all the required calculations and compared the students’ results to the theoretical value. This made grading the lab reports much quicker and more accurate, flagged incorrect student calculations, allowed a much more complete discussion of the lab results and permitted “what if” questions to be discussed.
In the lab, students are given a 1.5 gram samples of copper. The copper is taken through a series of five chemical reactions ending with the precipitation of solid copper. After the five reactions, students are asked to return their 1.5 gram samples of copper to the teacher.
Think it’s possible to get nostalgic over paperwork? I just did, spurred by editor-in-chief Norb Pienta’s editorial Thinking about Champions in the December 2015 issue of the Journal of Chemical Education.
There is a hydrate lab which is done by many teachers. Typically, students first use a known hydrate and are provided the formula. As an example, they might use CuSO4 . 5H2O. On paper, they would work through the percent by mass of water in copper (II) sulfate pentahydrate. They then would be given a mass of the copper (II) sulfate pentahydrate, calculate how much water they should lose and then they would heat it and compare the data with the calculated value. Next, they are given an unknown hydrate. They are also given the molar mass of the unknown salt of the hydrate and they have to calculate the molar ratio of salt to water based on their data. Here is one possible way to “tweak” this lab.
In this Activity, students investigate a classic chemistry demonstration that uses the phenomenon of freezing-point depression to lift an ice cube out of a glass of water with a thread. They first test how adding salt, pepper, cream, and sugar to cold water affects the temperature.