Multimedia Lab: Newton's 'Chymistry' of Metal Solubilities
Newton's chymistry was in many cases fully operational and explicable in modern chemical terminology. In order to drive this point home, we have prepared a lab unit, "Newton's 'Chymistry' of Metal Solubilities," that can be employed in schools as an integral part of their science education curricula. The lab unit is divided into three levels of difficulty, although the individual levels all build on the same simple reactions taken from "Query 31" of Newton's Opticks.
The first level, intended for Middle School science courses, involves basic observation of color changes as metals replace one another in solutions. In 2004-5, the exercises depicted here were successfully tested in the 8th- Grade science course taught by Nancy Martin at Jackson Creek Middle School in Bloomington, Indiana. The color changes appearing during the reactions can also be observed in two time-lapse sequences filmed in the laboratory of Cathrine Reck at Indiana University. The first sequence illustrates the reduction of silver from a silver nitrate solution while copper is dissolved in the solution. The second time-lapse sequence depicts the reduction of the previously dissolved copper while iron is dissolved. We recommend that interested viewers who do not have access to a laboratory or properly equipped classroom download the videos below so that they can see what Newton himself observed.
The second level of difficulty ("Extension 1"), intended for beginning High School students, adds a quantitative dimension by introducing the concept of molarity. Carrying out these calculations will give an excellent laboratory introduction to important concepts that the student will encounter on a regular basis in High School Chemistry.
The third level of difficulty ("Extension 2") introduces the concept of Redox, a normal component of advanced High School and beginning College Chemistry courses. The two time-lapse sequences that we provide are in fact examples of Redox reactions.
A medallion composed of a silver-gold alloy is dipped into nitric acid. Some of the silver dissolves, leaving gold. It looks as though the silver has been "transmuted" into gold.
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The "transmutation" is actually copper-plating of a steel sawblade in a solution of copper sulfate and water.
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In Newton's day, a silica garden was usually made by placing ferric chloride lumps in a solution of potassium silicate, as in the following demonstration.
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A crystalline growth emerges from a globular amalgam of silver and mercury in a solution of silver and mercury dissolved in nitric acid.
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Copper dissolving in a solution of silver nitrate while the silver comes out of solution in metallic form.
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Iron shot dissolving in the solution of copper nitrate formed during the previous reaction.
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