Dean Campbell's blog

Not so Green Up Close: a Peek at a dyed Chicago River Sample

Light absorbance and fluorescence were studied for a sample of the Chicago River that had been dyed green for St. Patrick’s Day. The sample had weak green fluorescence, showing that the intense green appearance of the river was in part due to the long path length of light through the water. The ability of the green color to partition into 1-octanol was also explored.

Egg-lectrons and McLewis Structures

Egg cartons and beverage holders can be used as models of atoms, with their dimples representing orbitals. Each dimple can hold up to two objects such as milk jug caps, plastic eggs, and cup pieces to represent electrons in the orbitals. Partially overlapping the trays by stacking the dimples represents chemical bonding and produces molecular models resembling Lewis structures. The models can be easily made from materials that can be readily found grocery stores and fast-food restaurants.

Fluorescence Rocks! Exploring Glowing Sodalite

Syenite rocks containing sodalite that fluoresce yellow have been found on Lake Superior beaches in recent years and are of interest to collectors. The fluorescence of this mineral, which can be found in other localities, can be shown in classrooms and studied spectroscopically. Its structure can also be modeled with LEGO bricks, enabling further classroom connections.

Amount and rate of heat transfer using iron spheres and liquid nitrogen

When iron spheres at room temperature are added to liquid nitrogen, the nitrogen boils as heat is transferred in from the iron. The amount of liquid nitrogen boiled depends on the amount of heat transferred, which depends on the mass of the iron added. However, the rate at which liquid nitrogen boils depends on the surface area of the iron in contact with the liquid nitrogen. These phenomena can be studied with experiments which measure the mass lost by the boiling liquid nitrogen.