Blogs

Using My Marbles: Connecting Surface Area and Calorimetry with Temperature Curves and Thermochromic Cups

The importance of surface area can be illustrated by adding spherical solids at known sizes and temperature to other substances at different temperatures and then monitoring the rates of temperature changes of the system over time. Larger spheres (with less surface area per sample) exchanged heat with water more slowly than smaller spheres, and less thermally conductive glass spheres exchanged heat with water more slowly than iron spheres. Additional, more colorful demonstrations are described in which small glass spheres cool thermochromic plastic cups more quickly than larger glass spheres. 

Seawater Chemistry and Global Trade: Part 4

Continuation of the practical application of chemistry to seemingly something unrelated- global maritime trade. In this classroom activity students predict the buoyancy (and hence stability) of a merchant cargo ship based on interpretation of seawater surface salinity values. Like in the first three posts, the question types are conceptual.