tranquilsea - 20 September 2007 09:25 PM

There is an on-line company called, “The Teaching Company” that packages various professor’s lectures from around the US in audio and/or video for sale.

Mentioned HERE; many professors affiliated with the Teaching Company also have worked with CFI. They provide a great resource. Highly recommended in general. Of course, individual courses may be better or worse ... (Although I haven’t yet found any that I’d “pan”).

FWIW I’m going through one of their courses on the History of the English Language. Generally I’d give it a positive review, though the coverage of the subject is little bit superficial. I haven’t tried any of the science courses yet.

mckenzievmd - 21 September 2007 09:59 AM

... coverage of the subject is little bit superficial.

This is one argument I’ve heard from some people about their courses. Perhaps it really is true of the one you’re watching, but some that I’ve watched that others considered superficial I had to ask how they would re-do the course to make it deeper in the same amount of allotted time. It’s a hard thing to do, especially given the fact that most of their courses are basically survey courses of one kind or another. So if you go too much into depth on one person or event you end up not talking about another at all ... and that’s often a tough decision to make.

FWIW, the one I liked the least was about the Enlightenment. Not to say it was a bad course (it wasn’t), but I thought the professor had the wrong approach to the subject matter.

Narwhol,

narwhol - 20 September 2007 01:45 PM

Hi Corey,

A reducing agent is a chemical that reduces an oxidised species.  Reduction is either loss of oxygen (e.g. Copper oxide (copper ore) becoming copper)

What do we see with our own eyes when smelting (reduction) takes place?  Is it reasonable for me to say that the constituents of the copper oxide (the ore) break up due to the oxygen escaping in the form of gas, while the copper itself drops into a liquid state?   

Copper ore is copper oxide.  Carbon is an element
Copper oxide + carbon forms copper + carbon dioxide

The only way I’ll be able to make sense of that is to visualize it in action.  What do I see with my own eyes when we smelt copper ore, and why am I seeing what I’m seeing?

In this case, the copper oxide has been reduced to copper by the carbon, so the carbon is called a reducing agent.

What percentage of the ore is copper?  Is it a very small percent?  If so, where does all of that excess mineral go?  What does the separation process look like, if I were to witness it? 

Conversely, the carbon has been oxidised to carbon dioxide by the copper oxide. 

So somehow, the carbon elements fuse with oxygen, creating carbon dioxide?

So the copper oxide is called an oxidising agent.

So for smelting to take place, on the one hand we need a reducing agent, and then on the other hand we need an oxidizing agent. 

Each, the oxidizing and reducing agents, have a structure.  The oxidizing agent, is a compound, whereas the reducing agent, carbon, isn’t.  The key is to, via heat, loosen the up carbon’s structure, as well as loosen up the structure of copper oxide, so that it’s components slip out of each others possession.  The oxygen gets sucked out of the possession of copper, into the possession of carbon.  When it’s heated, carbon is made capable of gaining possession of the oxygen. 

This happens because carbon is more reactive than copper so it is more likely to form compounds, whereas copper is more likely to be stable as an element (because it is less reactive than copper). 

Hmmm.  That interests me very much.  Why is one element more reactive than another? 

When a more reactive species displaces a more reactive species (as carbon displaces the copper from the copper oxide, to form an oxide of its own), it is called displacement.

If I understand you correctly, the copper oxide becomes vulnerable to being displaced because of the heat.  When the copper oxide(the ore) reaches a certain temperature, it’s components become loosened from each other, and thus, the oxide ‘slips out’, getting sucked out of copper’s possession, and into the possession of carbon.

Or am I way off here?

Doug,
I’m really interested in the courses generally, so I’ll make a thread devoted to that so this one doesn’t get too off track.

After more thinking and searching, it suddenly seemed quite vital to consider the invention & development of ceramics in relationship to the invention and development of the kiln.

Consider this excerpt:

“The earliest clay objects were earthenware—that is, hardened in an open fire. This “low fire” method results in a porous, relatively soft material, which is not waterproof.”

And then: 

“The next stage of development was the invention of the kiln—a type of oven in which temperatures much higher than an open fire can be obtained. This “high fire” method produces a type of ceramic known as stoneware, much harder and stronger than earthenware, and also waterproof, even when unglazed.”

Unfortunately, the people who wrote that little tidbit jumped a little too hastily for my liking (they weren’t intending to teach chemistry/physics, so it’s understandable). 

I’d like to know why the higher temperatures effect the clay differently than lower temperatures. 

Is the clay used for earthenware different from the clay used for stoneware?

ah, found an answer:

“Stoneware is made from a different clay than earthenware, and requires a higher firing temperature.”

That being said, my next question is, what are the factors which make these two types of clay different from each other?

I’ve just been informed about the first three types of ceramic manufactured by the ancients:

Earthenware (lowest quality, porous, not waterproof,  requires lower temperatures to produce)
Stoneware (higher quality, requires higher temperatures to produce)
Porcelain (highest quality - requires highest temperatures to produce)

Understanding the theory of Weathering I believe is the key to understanding what it means for clay to be of low, higher or highest qualities, and thus, why clays differ in how they respond to heat.

CoryDuchesne - 24 August 2007 02:11 PM

To put it in other words, I’m really interested in knowing what the first few chemicals were that were first discovered.

I would really recommend checking out related books by Isaac Asimov—google on “Asimov” “the elements” or check the bibliography below.

Here is one:
The Search for the Elements by Isaac Asimov (1962)

hmmm this probably dates me, doesn’t it. He also wrote monthly science essays for many years for the magazine of Fantasy and Science Fiction, which are quite readable. I remember one essay just on the chemical paradimethylaminobenzaldehyde, which he suggested you remember because you can sing it to the tune of an Irish jig.

These will be in the library…

(Asimov bibliography on Wikipedia)

Yeah, a few weeks ago I took a book out of the library called A Short History of Chemistry - by Isaac Asimov.

The first twenty or so pages were very useful to me, but after that, it took off too quickly for my liking.  I’m sure it will be a beautiful read once I fulfill some of my more fundamental curiosities. 

The little bit at the beginning of the book brought my attention to metallurgy, which, in regards to being a place to start, was a good one.  I now find myself interested in more fundamental issues about the geological/chemical processes that generate clay, and its vitrification.  Once I’m comfortable with that, I’ll probably dwell more on metallurgy again.

I encourage you to look over my most recent posts, and based on what you make of my interests, if you think you can be of assistance, then I’d appreciate any help you have to give.

Oh yeah, and I’ll be sure to check out: “The Search for the Elements by Isaac Asimov”

I never heard of that title until now.  It’s probably more suited for my interests.  I’ll see if the library has it and will trade the book I’ve already taken out by Asimov.

Your query is so general it is generating a broad discussion.

1. In regard to SALT - which was some of the sub-threads, there actually was a whole book written on the topic.
Link
Salt: A World History by Mark Kurlansky
My father-in-law was a chemist and left this book to us.

2. In regard to OXYGEN (“Slow Burn Oct 1962”) and HYDROGEN, I would recommend sections of Asimov books or the books of his essays.
Here is a link to a bibiliography of the essays
Bibliography of Asimov Essays (Fluorine, Mercury, Periodic Table, Chemical Nomenclature)
There are also essays on CARBON/Grapihte/diamond, HELIUM, etc.