The Mole Past Mole Day Themes

Mole Day 2011 Theme

Now that you’ve seen the size of a mole…consider these… Would a mole of rice fill the school? Would a mole of rice cover the city of Plymouth? Actually, if I had a mole of rice, all the land area in the whole world would be covered with rice to a depth of 75 meters!!!!

How much mass is a mole of hockey pucks? If each hockey puck is 125 grams, one mole of hockey pucks has a mass of 7.52 × 1022 g The mass of the moon is 7.349 × 1022 g – this means a mole of hockey pucks has more mass than our moon!!!

If had a million dollars (If I had a million dollars) … I’d be rich If had a million dollars (If I had a million dollars) … I’d be rich! (not really) But if I had a mole of pennies, I could Buy kite string at the rate of $1 million/inch, stretch the string around the earth one million times and to the moon and back twenty five times and with the left over string sold back at a penny an inch, I’d still have enough money to: Buy every man, woman and child in the U.S. a $5,000 car and enough gas to run it nonstop at 55 mph for one year and still have enough to give every person on earth $9,204 cash

Still on the penny idea A mole of pennies divided up equally among all the earth’s population would result in: Each person receiving 8.6 × 1013 pennies Personal spending at a rate of $1 million/ day would use up each person’s wealth in just over 2,350 years! Also, the pennies would cover the earth’s surface at a depth of 420 meters (quite uncomfortable!)

Why is the term mole officially abbreviated mol and not something shorter? I can only offer you my best guess as to why “mole” is officially abbreviated “mol”. Here it is. Most scientific abbreviations (ever wonder why this word is so long?) are 1, 2 or 3 letters long. When possible, we try to use letters that are already in the full length word. The lower case “m” is already used for both mass and molality. Since “mo.” already designates month and “ml (or mL)” is taken to mean milliliters it seemed reasonable to go the three letter designation “mol” which saves us either 1 letter (mole) or 2 letters (moles). Also, capitalization of the “m” in mole doesn’t work on two counts. First, mole is not the name of a person and generally, capital letters are assigned only for units that commemorate a person. (I know, there are violations of that rule.) Second, “M” already is used for molarity units or molar concentration units.

All of this is fancy talk for “I really don’t know for sure.” What is the origin of the chemical term “mole”? Was it originated by Avogadro? First of all, Avogadro did not use the term “mole”. Not only that, he did not come up with Avogadro’s Number. But his work did pave the way for the unit we call “mole”. The term was probably first used by Wilhelm Ostwald around 1900. The word is possibly derived from the latin “molus” which means “little pile”. Another source indicates the term “mole” may come from the German “molekulargewicht”. Some have even suggested that it is the fractionation of the word “molecule”. All of this is fancy talk for “I really don’t know for sure.”

What, exactly, is a “mole”? A scientific mole is really a number. You know that when somebody refers to a dozen cookies, that they mean twelve cookies. A “dozen” means “twelve”. In science, we use the term “mole” to represent “6.022 times 10 to the 23rd power,” which is a very large number. It is often written at “6.022 x 1023” or “6.022 x 10^23” or “6.022 E 23”. We use this number to count very small things like atoms and molecules. A mole of water is 18 milliliters of water. That is not very much when we look at it but it is a very large number of molecules of water. It represents an amount of material that is large enough to see and usually small enough to hold.

I’ve seen the numerical part of Avogadro’s number written as 6 I’ve seen the numerical part of Avogadro’s number written as 6.02 or sometimes 6.022. Since it represents a number of atoms or molecules, and assuming that it is a whole number with fractional remainder, what are the rest of the numbers (to the decimal point)? Mathematicians give us p to more than a million decimal places. Why don’t we know Avogadro’s number at least to the real decimal point?

First of all, there is a big difference between pi and Avogadro’s number. Pi is determined from a mathematical function and appears to be a non-ending number. So far, it has been calculated out to 6 billion places. Avogadro’s number on the other hand is ultimately the result of measurement or calculation based on measurement and that is where we have the problem. Significant figures apply to measurements or values that are calculated from measurements. The best value I have found for Avogadro’s number was in an article titled “The Fundamental Physical Constants” from the August, 1997 Physics Today. It gave a value of 6.0221367 x 1023 with a standard deviation uncertainty of 36 in the last two digits.

Why is the symbol “n” used for moles in equations such as PV = nRT? Most likely, the symbol “n” stands for “number of moles”.

Learning about Molar Mass Calculations with the mole converting mass to moles converting moles to mass converting number of particles to moles converting moles to number of particles converting mass to number of particles converting number of particles to mass

How to do calculations between moles, atoms or molecules, and grams of a substance? One of the main problems that beginning chemistry students have is in doing conversions between grams, moles, and molecules (or atoms). Usually, a question will be asked of you in the following form: How many moles are in 22 grams of copper metal? If you're confused by this problem, don't worry. Most people are when they start doing this kind of problem. To make life easier for you, I put together a "road map" which tells you exactly what you need to do to convert between atoms (or molecules), grams, and moles.

What is are the values written in green? The first is Avogadro’s number = the mole. This is what the notes have been about thus far. The second is the molar mass. Molar mass is the mass of one mole of an element or compound. You determine the molar mass by looking at the average mass number on the periodic table. If we are dealing with a compound/molecule, you add the masses of all the elements together.

The Four Steps to Solving Mole Problems: Step 1: Figure out how many parts your calculation will have by using the diagram Looking at the diagram below, we can see that we are going between grams and moles, which is a one-step conversion. Furthermore, we can see that we need to use the atomic mass of copper as our conversion factor.

Step 2: Make a T-chart, and put whatever information the problem gave you in the top left. After that, put the units of whatever you were given in the bottom right of the T, and the units of what you want to find in the top right. In this case, the problem gave you "22 grams of copper" as the starting information. Because this is what you were given, put "22 grams of copper" in the top left of the T. Since "grams of copper" is the unit of what you were given, put this in the bottom right of the T. Since you want to find out how many moles of copper are going to be made, put "moles of copper" as your unit in the top right. When you've done this, your calculation should look like this:

Step 3: Put the conversion factors into the T-chart in front of the units on the right. As we saw from the "map", the conversion factor between grams and moles is the atomic mass of copper. Because we measure atomic mass in grams, you need to put the atomic mass in front of the unit "grams of copper". What do you put in front of moles? Whenever you do a calculation of this kind, you need to put "1" in front of moles, like you see here:

Step 4: Cancel out the units from the top left and bottom right, then find the answer by multiplying all the stuff on the top together and dividing it by the stuff on the bottom. In this case, you'd multiply 22 by one and divide the result by 63.5. Your answer, 0.35 moles of copper:

Now it’s time for us to do a few problems on paper… Handout from Mrs. P.

Tutorials … if you have any questions http://www.chemteam.info/Mole/Mole.html http://www.onlinemathlearning.com/mole- calculation.html Http://misterguch.brinkster.net/molarmass.html Website with ppt tutorials

I pledge allegiance to the mole, to the International Union of Pure and Applied Chemistry, and to the atomic mass for which it stands, one number, most divisible, with atoms and molecules for all.   (Provided by Sylvia Cooper - Morgantown High School, Morgantown, WV) http://www.moleday.org/htdocs/moleinfo.html

Here Endeth the presentation, but never The Mole