The purpose of this variation on the “dragon’s breath” demonstration is to illustrate that face masks can diminish the movement of particles in the air, an important idea in public health.
rate of reaction
This experiment in chemical kinetics can be conducted using materials as simple as a smartphone, hydrogen peroxide, sodium carbonate solution, and blue food dye! The experiment is useful when discussing the order of rate laws with respect to reactants.
A classroom activity to demonstrate the principles of chemical kinetics and equilibria and the utility of the mole concept is described here. The activity involved no hazardous materials or complex equipment and can be enjoyed and appreciated by general studies students as well as chemistry majors.
Whether you are introducing collision theory or something more demanding like reaction order, the reaction between sodium thiosulfate—Na2S2O3 and hydrochloric acid can provide a consistent, accurate, and engaging opportunity for investigating these topics.
I taught my students how to use the method of initial rates. I taught my students rate laws. However, they strugged to differentiate when to use what method. Upon further probing, they struggled to articulate why one might use one method over the other. They could parrot back some ideas ("The rate law tells you about the particles involved in the rate determining step of the reaction."), but I wasn't convinced of mastery and connections.
I am facing what many teachers are facing. It is AP week, I am trying to continue "as usual" with doing labs and learning but this time of year is anything but "as usual". There is a rates lab we do this time of year which is a good lab, rather involved with a significant amount of set up and work. I got an idea for a slightly different rates lab from Bob Worley. I found a similar large scale version from Flinn Scientific. Thanks to Bob, I decided to do a microscale version.
In one of my last blog posts I wrote of how I sometimes enjoy ending a unit with a series of demonstrations and using them to elicit a dialog between the students and myself to check for understanding. It is always a fascinating experience to hear the misconceptions that many students have the day before the test.
In this Activity, students compare the combustion of different substances such as a glowing wooden toothpick and lit birthday candle in air, oxygen, exhaled breath, and carbon dioxide environments. The oxygen and carbon dioxide are generated from supermarket chemicals. This Activity can be used to explore the chemistry of oxygen and combustion.
In this Activity, students observe and compare the behavior of three lightsticks that are exposed to three different temperature ranges (cold, room temperature, and hot). The Activity could be used early in the school year to give students practice in making detailed observations and devising reasonable explanations for those observations. It illustrates the use of qualitative vs.