04: ChemCollective Virtual Lab

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This semester students will be using the ChemCollective Virtual Lab that was developed by David Yaron at Carnegie Mellon University. This lab was initially known as the Irydium project and required Java, but around 2016 was ported to HTML 5 and can be used on most web browsers without downloading anything. We can look at the Virtual Lab as a "Window's Intuitive" GUI (Graphical User Interface) where students can drag and drop reagents from a stockroom to a lab (work) bench and mix them in a manner that allows them to obtain computed data on the products created through an information panel.

The following 3:28 video was developed at Carnegie Mellon and quickly goes over the use interface of the virtual lab. Please watch this video before you use the virtual lab. In the video you will see several transfer modes. Most of our activities will involve the "precise mode" where the quantity of reagent transferred is precisely what you type.

Video \(\PageIndex{1}\): Short 3:28 tutorial on the use of the virtual lab

We will typically use the virtual lab in pre and post lab activities that contain "unknowns" that students are assigned to work with, and so the chemicals in the stockroom will vary from activity to activity. The following is the "default virtual lab", which contains the normal stockroom.

The virtual lab uses thermodynamic properties like enthalpy, entropy and specific heat capacities to predict the equilibrium distribution of chemical systems after a reaction. We will actually be covering the equations the lab uses this semester and there will be activities where we use the virtual lab to calculate the free energy, entropy and enthalpy for chemical reactions. The virtual lab operates in an ambient environment of 25^oC and the temperature of a flask involving an exothermic reaction would rise and then slowly return to room temperature. One can "thermally isolate" a reaction flask by right clicking and choosing the appropriate option, in which case the system will not transfer heat to the environment and return to room temperature.

There are sort of two approaches to assignments using the virtual lab. The first is to emulate the real lab and sort of be a substitute for it, and the second is to run it as an "ideal lab", as sort of an alternative to the real lab and take advantage of differences between the real lab and the virtual lab to gain a better understanding of the real lab. At UALR we will run prelabs and postlabs that follow both approaches. The very first virtual lab deals with the temperature dependence of saturated solutions and the "technique" in the virtual lab is completely different than in the real lab, and this gives the students a chance to think about what they are doing. In the real lab you can not easily measure the mass of the precipitate, while in the virtual lab you can instantly read the mass of the solid. Although you could filter and dry the precipitate in the real lab, you would need to do that while maintaining a constant temperature to avoid the solubility from changing while you were filtering the solution, and that would be very difficult to do. In the virtual lab it can be done in the flash of a second, you simply read the mass of the solid under the supernatant.

Another example of the difference between the real lab and the virtual lab can be seen in calorimetry (section 5.6). In the real lab you have to take into account the heat absorbed (or lost) by the calorimeter itself, and this is typically done by running a secondary experiment to calculate a calorimeter constant. In the real lab the heat released in an aqueous exothermic reaction is absorbed by both the solution and the calorimeter, while in the virtual lab the flask absorbs no heat, and so the temperature change in the virtual lab would be higher than in the real lab. That is, the virtual lab has an "ideal" calorimeter that absorbs no heat, which is impossible in the real world.

The bottom line is that chemistry uses equations to predict how chemical systems will behave, and those equations are based on theoretical models. There is a limit to the validity of any model and part of the practice of a science is knowing which model to use and when to use it. The ChemCollective virtual lab uses many of the equations we cover in this course to provides a simulation, which can be used to practice the the material covered in this class. But by comparing the results of the virtual lab to the real lab we also have a chance to develop a better understanding of those models and their applications to real world science. At UALR we will use the virtual lab in both contexts. That is, some of the post lab assignments will allow us to perform experiments we did not have time to cover in the lab, and others will emulate the exact experiment we covered in lab, and provide a chance to compare the results of the real lab to the virtual lab and gain a better understanding of the science.