Microfluidics for Personalized Reactions to Demonstrate Stoichiometry

Abstract

Stoichiometry, the ideal gas law, and the concept of limiting reagent are challenging principles for students to conceptualize in introductory chemistry. These topics are fundamental to successfully mastering other chemistry content. Therefore, a handheld microfluidic device was designed as a new tool to visualize these principles. Using food-grade baking soda, vinegar, and carbonated water as reagents, the students were engaged in a hands-on learning experience. The baking soda and vinegar were the source of sodium bicarbonate and acetic acid which were combined in a 1:1 mol ratio to form carbon dioxide gas which was then quantified using the device, thereby illustrating the ideal gas law. Experiments were devised to support learning outcomes that involved using the ideal gas law to interconvert moles and volume, balancing chemical equations, quantifying the amount of product generated from a known amount of reactant, conveying measurement uncertainty, and postulating sources of experimental error. The microfluidic device is a fast and cost-effective tool to teach stoichiometry. Moreover, the use of food-grade reagents makes the activity accessible as well as safe enough to be conducted outside of a traditional laboratory setting.

Determination of Reaction Stoichiometry by Applying Job’s Method and Digital Image Processing for Precipitation Reactions

“…3 Besides numerous absorbancebased applications, 4−6 the volumes of evolved gases were measured to determine reaction stoichiometry. For instance, a hand-held microfluidic device was used to measure gas bubble expansion in calibrated capillary channels, 7 while in an other case the displacement of the so-called Dalton syringe rocket propelled by the exhaust gas was explored as the function of the composition of the fuel−oxygen gas mixture ignited inside the syringe. 8 One may find only a very limited number of examples for applying precipitation reactions to illustrate Job's method for the determination of reaction stoichiometry.…”

“…According to the above, precipitation reactions can be applied as a catchy and well-visible demonstration for the determination of reaction stoichiometry via Job’s method, if the following criteria are fulfilled: (1) The experiment can be completed in a significantly shorter period of time, and (2) large enrollment chemistry classes necessitate the use of diverse themes, i.e., various unknown systems …”

Controllable Preparation of Monodisperse Chitosan Microspheres Based on Microfluidic Technology

“…Because of the uniform and controllable size of the generated droplets, microfluidics is widely used in detection and diagnosis, − single-cell analysis, high-throughput screening, − drug development, , and the manufacture of functional particles. Current education articles on microfluidics mainly introduce continuous microfluidics, − while there are few educational articles on droplet microfluidics. , Continuous microfluidics is based on the control of continuous flow in microchannels. Droplet microfluidics refers to the technology of generating and controlling droplets (a discontinuous phase) by generating them in the presence of an insoluble liquid (a continuous phase) in microchannels.…”

Think and Print: 3D Printing of Chemical Experiments

“…Predominantly still used for the illustration of orbitals and molecules in teaching, , more recent publications have also broken new ground in developing or using chemical reactors in university teaching using 3D printing. , Printable experiments would, therefore, offer a cost-effective, innovative, and holistic variant for exciting projects in both university and school teaching.…”