Talk:Mole (unit)

intro prompted by comments on the forumsGareth Leng 12:46, 28 November 2007 (CST)

Re: "(clear language intro??)" No question Gareth, it does read more clearly.--Thomas Simmons 14:41, 28 November 2007 (CST)

not a textbook

I rewrote the introduction, and removed the worked-out example from the article. The example added unnecessary bulk to the article. Anthony Argyriou 18:16, 28 November 2007 (CST)

Can't agree with the rationale here for the removal of the 'textbook' style text. The assertion that this is not a textbook to make sweeping deletions, and I do mean large patches of text, is to be discussed here, not simply a decision to be reached by a single author. I have taught chemistry at the high school and the undergraduate level and can say from experience that as a basic concept in chemistry it is imperative that it be comprehended. Writing for more than one level of understanding is very much a function of a viable encyclopaedia. I have had a number of students here in New Zealand and in the States as well as teachers at those levels read this for their comments and the extended version definitely reaches a broader range of levels of understanding. The amended intro has received varied comments which indicates to me that it is reaching a higher level of understanding--basically those who already know what a mole is. It is the extended text that is giving vital concrete information so that the concept is generalised by the reader and that is needed to support the technical level of the introduction. In other words, if you know what a mole is, why consult an encyclopaedia? Furthermore, many of our better articles are certainly capable of being used as textbook texts. The biology article for example, has received good feedback from students and it certainly uses an expository register as one would expect in a competently written textbook. Please bring any objections to text and context to the discussion page before making such large deletions, as is the normal procedure here on CZ. --Thomas Simmons 16:17, 29 November 2007 (CST)

RE: Paul Wormer's rewrite: I think it reads very well. Explains some of the older references the reader might encounter to a greater degree as well. --Thomas Simmons 19:11, 4 December 2007 (CST)

I've gone through and corrected a number of mistakes and clarified the text of the article. The "textbook" examples are rather confusing and have fairly low content - if there are to be examples, they should be clear and more practically useful. I have separated the examples into a separate section, but have not made any changes. Anthony Argyriou 23:20, 7 December 2007 (CST)

• Why did you delete the few words that remind the reader that a mole of water is 18 mL? Further you undid the high school-type mnemonics in the "loose" definition: a mole weighs as much as the molecular weight. I put both in inspired by the forum discussion on this subject, which taught me that this sort of thing is appreciated by non-scientists.--Paul Wormer 03:39, 8 December 2007 (CST)

The density of liquid water isn't relevant to the discussion of the concept of mole. The result that one mole of any gas occupies the same volume is far more interesting, and should stay, but pointing out that one mole of particular liquid will have a volume numerically equal to its mass is potentially confusing as most other liquids do not have this property. I'd missed the parallelism between "weight" and "molecular weight", though I'm not sure quite how useful that is, as it propagates an error (mass != weight). Unfortunately, the term "molecular mass" is uncommon, even though "atomic mass" is used as much as "atomic weight". Anthony Argyriou 10:44, 8 December 2007 (CST)

This makes the point that any constable or editor would have made, discuss these changes when they are substantive. If the density of water can clarify the issue then it is a supporting concept. So assertions about what is relevant and what is far more interesting are to be discussed here before deletions are made. Tangents are not necessarily distracting if they help the reader understand. --Thomas Simmons 17:44, 21 December 2007 (CST)

• (1) Most people have an idea about an amount of water, and 18 mL (if I had known American measures, like teaspoon, etc. I would have added that) illustrates how much a mole of water is. (2) Lots of people, even scientists, still say something "weighs" some grams. But I added a sentence (that you removed) explaining that one shouldn't. --Paul Wormer 10:56, 8 December 2007 (CST)

He has a point, not so many years ago a lot of people were being told "molecular weight in grams." It is still being used. The reason is that most people figure weight in mass units not weight units even though they do not know it. Less of a heavy hand with the deletions please. --Thomas Simmons 17:44, 21 December 2007 (CST)

Testing readability

I had a couple of high school graduates read this, both scored well into the upper 700s on all three sections on the SAT and with four years of science and chemistry in a very good high school in the midwest. Their eyes glazed over when they got to this section: The total mass of an amount of substance is the sum of the masses of its entities. For example, consider a pure substance B of entities with molecular mass M(B) u ( u is unified atomic mass unit). Recalling that 1 u = 1/NA gram, we find that one mole of B weighs NA × M(B) u = M(B) gram.

For example, "entities" is used in common lanaguage as say deities, super natural beings. The use of commonly understood words is to be encouraged but when they carry wholly different meanings it is obfuscating.

Another problem is that the equations need to be written out as well. How long after they start reading equations are they still having trouble reading them? Spelling them out here would be a good way of reaching the targeted audience. Remembering that those who know what a mole is will not be reading this to learn how to calcualte molarity etc.--Thomas Simmons 17:44, 21 December 2007 (CST)

As a further test, could you ask your readers to read this older version of the article and ask them for their opinion of that text? That's the last version before examples were added. Anthony Argyriou 18:02, 21 December 2007 (CST)

edits on 21 december 2007

Thomas - the edit you've made to the article, adding:

and is used to signify how much or how many just as one would use "one kilogram" or "one dozen". It is a very large number however and it is used to indicate amounts of molecules or single atoms of substances. Since they are very small (a drop of water might contain trillions of molecules) the number is correspondingly large.

appears to detract from the article much more than improving it. Firstly, the tone really strikes me as talking down at the reader. Secondly, it introduces several inaccuracies and ambiguities. A mole is technically a count, therefore "just as one would use one kilogram" is not truly accurate - a kilogram of carbon is a different number of moles than a kilogram of uranium, while a mole of each is the same number of atoms. It's true that a drop of water contains "trillions" of molecules; in fact, a 1ml drop of water contains tens of millions of trillions of molecules. It would be better to explain the magnitude correctly than to just wave around numbers like trillions. Thirdly, the placement of the edit interrupts the previous flow of the article, and the edit essentially duplicates the former second paragraph. I'm refraining from reverting or hacking up your edit, but I hope you will take a second look at it and revise the article in a way which improves it. Anthony Argyriou 18:42, 21 December 2007 (CST)

Well, first, it may appear to detract but it does not. Having used this approach myself to good effect and having seen others using it at the high school and undergraduate level and consistently by those who get rated highly by undergraduate students for effective teaching, it is a clear and concrete way to get the message across, the concept is about a means to quantify and as such is not some strange new and complicated language. It reassures the reader that they are dealing with something they can understand and the more knowledgeable will know that the writer is adjusting it for the level it will most effectively serve, the people who are new to the concept.

And no, I do disagree, the people who will read this to learn will not feel they are being talked down to. Using clear language and building on what they already know is effective in teaching. And yes a mole is a count but more importantly it is a means to signify quantity as are the well-known examples ‘a dozen’ or ‘a kilogram’. Quantities, be they mass or enumerated are quantities. The lexical import is hypernymic.

Splitting hairs over trillions and millions of trillions could be obfuscatory but on the other hand the point is to impress upon the reader that the concept is essential when dealing with a very large number of very small things.

Concept complexity is effectively taught by building on known concepts. The introduction starts at an introductory level, makes the point that the topic is about a means to indicate quantities, drawing upon commonly known concepts and then the continuation gets more complicated having set the stage so to speak. It builds in complexity and as such allows the reader to start at the beginning and not at the middle. So, no, I can not agree that it interrupts the flow of the article. It does place it in context before continuing on.--Thomas Simmons 23:10, 21 December 2007 (CST)

Large number?

Thomas, you write:

[...] the mole [...] is used to signify how much or how many just as one would use "one kilogram" or "one dozen". It is a very large number [...]

but you mean to say that the number of molecules in a mole (Avogadro's number) is a large number. You don't say "one kilogam" or "one dozen" is a large number, do you? One mole water is 18 mL, compared to the Atlantic ocean this is not a large number. --Paul Wormer 05:38, 22 December 2007 (CST)