HAZWOPER Heat

HAZWOPER is a government-invented acronym for HAZardous Waste OPerations & Emergency Response). To become federally “HAZWOPER-certified”, you must first take a 40-hour course. Thereafter, you must take annual 8-hour refresher courses to remain certified. By the time I retired, I had taken the original 40-hour course and 18 of the annual refresher courses.

The class instructor always handed out HAZWOPER Student Workbooks at the beginning of the course. The workbooks always contained a section on “Fires and Explosions”, which I considered to be one of my areas of expertise. That section of the workbook contained a fill-in-the-blank statement that said, “The degree of heat required to initiate combustion is called the: ____________.” The official workbook answer was “Ignition Temperature.”

I have always been somewhat demanding when it comes to accuracy in educational texts, and I’ll tell you that seeing that statement, “The degree of heat required to initiate combustion is called the “Ignition Temperature”, never failed to offend my scientific sensibilities. This is because heat is not temperature. Heat and temperature are two different things. Heat is a form of energy. Temperature is not. Temperature is merely a measure of the degree of “hotness”.

I give you this, from page 18 of Introduction to Chemical Engineering Thermodynamics, Third Edition, by J.M. Smith and H.C. Van Ness, McGraw-Hill Book Company, 1975: “One notable advance in the theory of heat was made by Joseph Black (1728-1799), a Spanish chemist and collaborator of James Watt. Prior to Black’s time, no distinction was made between heat and temperature.”

The first time I read this, I was astonished to learn that people had not always made this distinction. To me at the time, the distinction seemed obvious, although I knew that was probably because the knowledge of it had been around for more than two centuries. Things always seem easier after someone else has figured them out for you. The arrogance of humans is often manifested in feelings of superiority to those who came before us. For example, we might think we are smarter than the cave man was, but it may well be that if the cave man had not already figured out how to make fire, how to make tools and arms, etc., we would be living no better off than he did. To us accrue the benefits of all the advancements in knowledge that humankind has made throughout history. But I digress.

To clearly understand the difference between heat and temperature, it is useful to imagine that you have a one-pound hunk of iron at a temperature of 1,000 degrees F, and you drop it into a tub containing a million pounds of water at 60 degrees F. What does your intuition tell you the final equilibrium temperature of the water will be? Not much more than 60 degrees F, right? This is because your one-pound hunk of iron, hot though it is at 1,000 degrees F, is much too small of a mass to significantly increase the temperature of a million pounds of water. But now imagine, instead, that you have a million-pound hunk of iron at a temperature of 100 degrees F, and you drop it into a million pounds of water at 60 degrees F. Now what do you think the final equilibrium temperature of the water will be? Common sense tells you that the final temperature of the water will be considerably higher than 60 degrees F, right? So, what this also tells you is that although a one-pound hunk of iron at 1,000 degrees F is a lot hotter than a million-pound hunk of iron at 100 degrees F, the latter contains much more heat.

I rest my case.