Introduction

Michael Faraday's Lectures: A Chemical History of a Candle

At the Christmas holidays of 1825, Michael Faraday, the first (and foremost) Fullerian Professor of Chemistry at the Royal Institution of Great Britain, instituted the Christmas Lectures, a series of scientific presentations directed expressly to young people -- a series that continues to the present. The original objective of the lectures was to present science to the general public, and particularly to youths, in the hopes of inspiring them to practice and support science (and also to generate revenue for the Royal Institution). Faraday himself delivered the lectures 19 times between their inception and 1860. In 1948, he called his lecture series "The Chemical History of a Candle". Here's what he said about his subject:

“There is no more open door by which you can enter into the study of science than by considering the physical phenomena of a candle.”

The text, with Faraday's illustrations, are still available.    
• Free pdf version, including Faraday's drawings (most free internet versions do not have the drawings)
• Same version, paperback, from Amazon

To learn more about Faraday's life and work, as well as subsequent development of his visionary ideas on electricity and magnetism, see Faraday, Maxwell, and the Electromagnetic Field: How Two Men Revolutionized Physics, by Nancy Forbes and Basil Mahon.

Recently Bill Hammack, Don DeCoste, and Alex Black of the University of Illinois produced a video re-enactment of Faraday's lectures, using much of his original text and modernized demonstrations. The series is available free on YouTube.

Watch this introduction to the re-enactments of Faraday's lectures:

Read or Watch

• The Meaning of Chemical Formulas and Equations

In his lectures, Faraday did not give chemical formulas and equations. I will provide pertinent examples of both to help us talk more specifically about what's going on in his demonstrations. Here is a brief introduction to formulas and equations.

    Formulas
The chemical formula of a substance, such as the compound water, shows the number of atoms of each element in each molecule of the substance. The chemical formula of water is H2O, which means that each molecule of water comprises 2 atoms of hydrogen (H) and one atom of oxygen (O). The chemical formula of oxygen, as it exists in the air, is O2, which shows that the stable form, and most common form, of oxygen in air is a molecule, containing 2 atoms of the element oxygen. (For reasons we might discuss later, oxygen atoms are more stable as two-atom molecules than as free atoms.)

    Equations
Chemical equations describe changes, or chemical processes. The following equation shows the formation of water from the elements hydrogen and oxygen, both of which exist normally as gaseous molecules containing two atoms.

This equation, which describes two reactions in sequence, says that the reaction of two molecules of hydrogen gas (g) with 1 molecule of oxygen gas produces (-->) 2 molecules of water in its gaseous form (g), which then condenses to produce (-->) water in its liquid (l) form. To the left of each arrow are the reactants of the reaction, and to the right are products. All chemical reactions are of the form

    reactants --> products, or reactants --> intermediates --> products

Finally, a proper chemical equation is balanced, which means that it shows the same number of atoms of each element on both sides of the equation, because atoms are neither created nor destroyed during a chemical reaction. Notice that the equation shows four atoms of H and 2 atoms of O as reactants and as products.

In balancing a chemical equation, you are applying a simple conservation law. Conservation laws tell us what does not change during change (!?). Chemical conservation laws help us to see what is possible and what is impossible in a chemical reaction. During a chemical change like the one shown in the equation above, the thing that does not change is the number of atoms of each element. If hydrogen or oxygen atoms in the reactants is not the same as that in the product, then the process described by the equation is implausible -- it's simply impossible.

• Read this poem

The Abacus and the Rose, Jacob Bronowski

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• What are ATOMS, and how do we know about them?