Cellulose nitrate (also known as nitrocellulose or guncotton) is a very flammable substance that is formed by reacting cellulose (also known as dietary fiber) with a mixture of concentrated nitric and sulfuric acids:
JCE ChemEd Xchange provides a place for sharing information and opinions. Currently, articles, blogs and reading lists from ChemEd X contributors are listed below. We plan to include other items that the community wishes to share through their contributions to ChemEd X.
Whenever a serious incident takes place in a school chemistry laboratory or classroom, fire and safety officers often pontificate on the incident by quoting the Materials Safety Data Sheet (MSDS). However, how many of you have read such documents in full? In UK schools we have perhaps 200 to 400 chemicals on the shelves. Have you read the MSDSs for each chemical?
TV and movie screens today offer us a desperate fight against crazy-fast zombies, a peek into celebrities’ lives where truth is often stranger than fiction, million-dollar game shows, and more. Can portraits of science compete?
In a recent contribution to ChemEd X "Stoichiometry is Easy", the author states that he has "vacillated over the years between using an algorithmic method, and an inquiry-based approach to teaching stoichiometry. " I would like to suggest that there is another approach to mastering stoichiometry and that it should precede the algorithmic one: it is the conceptual approach based on a particle model to represent the species involved in chemical reactions.
This article describes a three week lesson plan for teaching stoichiometry using an algorithmic method. Two labs (one designed as a laboratory quiz) several cooperative learning exercises, student worksheets and guided instructional frameworks (forcing students to develop good habits in writing measures and doing problem solving) are included. The highlight of the lessons is the "chemistry carol" (based on Felix Mendelssohn's music for "Hark! The Herald Angels Sing") in which students recite a five-step algorithm for completing stoichiometry problems. While algorithmic processes may not always be best, I have found that there are many benefits to giving students a firm background and something to always fall back upon in one of the more challenging topics of chemistry. I believe that the good habits developed in this method of stoichiometry carry through to all the rest of their chemistry work, making it much easier to use inquiry-based methods when doing other advanced chemistry topics.
This worksheet is intended to be used as a "Guided Instructional Activity" (GIA). Students read a statement that gives a either a conversion factor or a pair of related measures and then write the information as two equivalent fractions ("conversion factors") and as an equality. In each representation, students are directed to give the numeral of the measure, unit, and identity of the chemical.
35 to 45 minutes.
Engaging and Sustaining Students' Interest in Chemistry The November 2014 issue of the Journal of Chemical Education is available online to subscribers at http://pubs.acs.org/toc/jceda8/91/11. The November issue content includes content on water chemistry, diversity and women in science, professional development, teaching with technology, electrochemistry, and more.
Last Thursday (11/6/14) I attended a workshop on NGSS through our local RESA (essentially an ISD for the county/region). I’d like to touch on some of the things I took away from this workshop and will post again after the next follow-up workshops in December and March.
This set of three worksheets are intended to be used as collaborative "Guided Instructional Activities" (GIAs). Two students cooperate to complete the steps of a stoichiometry problem, alternately doing parts of the process as they explain what they are doing and evaluate their partner's work. These worksheets emphasize an algorothmic approach that helps students learn to think aobut the purpose of a question, organize their work, set it up so that it is easily readable and can be followed by others, and make good use of "unit analysis" (dimensional analysis).
Each of the activity worksheets requires 40 to 55 minutes.
The three "Guided Instructional Activities" in this activity are three cooperative learning pieces in which students are guided through the process of converting from one unit to moles (or moles to a unit) by the method of "unit analysis" (dimensional analysis). Students alternate steps in the process and evaluate the success of each step. They must do things such as writing the given information correctly, finding the correct molar mass, setting up the mathematics correctly, and determining the answer to a required number of significant figures.
Each of the activities requires about 40 to 55 minutes. The first one used usually takes longer, the last goes quicker.