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KoolAid and similar drinks as convenient laboratory reagents: The weak acid-strong base titration of citric acid or malic acid

David Cash | Fri, 05/13/2022 - 08:06

The major component of a non-carbonated drink such as KoolAid or a similar beverage is usually a fruit acid, either citric acid or malic acid. The titratable acid (H+) concentration of such drinks has been found to be in the range of 0.02 to 0.04 M. A weak acid-strong base titration of these drinks with 0.1 M NaOH solution is feasible as a student exercise. Phenolphthalein indicator may be employed so long as the drink is not intensely coloured. The use of such drinks as reagents is safe, convenient, and inexpensive. Experiment instructions are included. 

Paper Snowflakes to Model Flat Symmetrical Molecules

Dean Campbell | Wed, 04/06/2022 - 13:39

Flat, symmetrical molecules can be modeled by folding a sheet of paper, cutting patterns into the folded structure, and unfolding to produce the flat paper models. The finished models resemble paper snowflakes, but have a variety of rotational symmetries. Template patterns for several molecules are available for download in the Supporting Information.

A short investigation of the use of pumpkin seed extracts in peroxyoxalate chemiluminescence demonstrations

Iain Smellie | Sun, 03/13/2022 - 13:19

In recent years, the fluorescence properties of pumpkin seeds have been highlighted on social media. When illuminated with a UV lamp, pumpkin seed extract appears orange/red to the human eye due to fluorescence associated with protochlorophyllide that is present in the seeds. Chlorophyll extracts can also be used as a fluorescent dye in “glowstick” chemiluminescence experiments. The similarities between chlorophylls and protochlorophyllide raised the question, is it possible to use pumpkin seed extract as a fluorescent dye in chemiluminescence experiments? In this short article, some results are reported from attempts to use pumpkin seed extracts for chemiluminescence experiments. 

Expanding on Self-Inflating Balloons: Activities Involving Moles, Gas Laws, and Thermochemistry

Dean Campbell | Thu, 02/10/2022 - 08:42

Balloons that inflate using carbon dioxide produced from the reaction of citric acid and sodium hydrogen carbonate can be used to demonstrate a number of aspects of chemistry. Gas laws were used with the balloons to illustrate limiting reactants, molar mass of gases, and rockets. The endothermic reaction in the balloon was visualized with an infrared camera, and the Green Chemistry aspects of these balloons were considered.