How Can We Determine the Exact Proportions in Which Two Chemical Substances React? 1. The challenge In many professions it is necessary to calculate quantities with precision. A tailor estimates the amount of fabric needed to make a garment, and…
Is It Possible to Calculate the Size of a Molecule Without Seeing It? 1. The challenge We cannot see a molecule with the naked eye. So how do we know how large it is? Science answers this question in a…
How Can an Ordinary Material Like Flour Cause an Explosion? 1. The challenge The key idea is surface area. When a combustible material is dispersed into very fine particles, each particle becomes surrounded by oxygen. If a source of heat…
How Can a Chemical Reaction Produce the Force Needed to Launch a Rocket? 1. The challenge When two substances react chemically, they can produce new materials and release energy. In this experiment, vinegar (acetic acid) reacts with sodium bicarbonate and…
How Can Air Change the Color of a Chemical Solution? 1. The challenge In this experiment, a series of oxidation–reduction reactions takes place. Dextrose (glucose) can donate electrons and act as a reducing agent, while methylene blue functions as a…
