Fourth Grade Chemistry
Studying the structures and properties of matter can be very helpful in understanding life on earth and the phenomena we observe. Simply said, studying chemistry helps us understand what happens within living organisms as well as the concepts we learn in physics. It can be so well integrated that sometimes discoveries made in chemistry are made by physicists and vice versa. This is true for the discovery or experiment that proved the concept that heat and mechanical energy are mutually interchangeable, and in fact have corresponding equivalent values. The Mechanical Equivalent of Heat, a paper published by James Prescott Joule, describes this concept, which later on led to the law of conservation of energy which states that energy cannot be created or destroyed within a system
Julius Robert von Mayer & James Prescott Joule
The saying that great minds think alike can probably best describe the case of Julius Robert von Mayer and James Prescott Joule. Independently, both scientists came up with the idea that heat and work are equivalent.
In von Mayer's case, he noticed a general equivalence between heat and work during his study of living things, in particular sailors who travel to the tropics. He noted that energy conversions take place among living things. For example, plants turn sunlight into food. Among the sailors, he noticed that their blood was redder in the tropics than in Europe. He attributed this to the warmer climate of the tropics, and so the body had to work less. He then realized that body heat and the amount of work (needed to be done by blood cells to keep a body warm) is interconvertible. This means than within the body, energy is always transformed from one form to another and is equivalent to the amount of work done by the organism. Von Mayer's work was not given much credit during the time he announced his findings, but he was a contemporary of Joule in finding this relationship between heat and other forms of energy.
Joule, on the other hand began studying the amount of work done in relation to the heat generated by electricity. He had originally planned on finding an infinite source of power through electric motors. Instead, he noticed that the heat generated by an electric motor was proportional to the amount of work done by the motor itself. The experiment he used for this finding was the famous paddle wheel experiment, in which weights are dropped in order to churn water. As the water churns, the temperature ofthe water rises. This led him to believe that energy was being transformed as the motor worked, from electric energy to heat energy. Furthering his conclusions, Joule was certain that a closed system has a total amount of energy that can be converted from one form of energy into another, and this total remains constant.
Both Joule and von Mayer had significant findings in the world of science and neither of them were chemists. However, their discovery is greatly used in chemistry when calculating chemical reactions and chemical energy. Today, the law of conservation of energy, also known as the first law of thermodynamics is used by many science researchers, experimenters, and inventors.
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