Mole ConceptChemistry: Foundations and Applications, (2004) by Nathan J. Barrows Adapted to PPT by Dr. F. Anthony Fiala
Chemistry: Foundations and Applications Most of the information in this tutorial is from the above journal (C:F&A) which covers chemistry, its laws, processes, applications and sub-disciplines. C:F & A reviews the history of the field, from the Bronze Age and alchemy up to modern research and practical applications. This informative journal includes biographies of scientists past and present.
Not This Mole! Moles are members of the family (Talpidae) of mammals in the order (Insectivora) that live underground, burrowing holes.
Mole Concept In chemistry the mole is a fundamental (SI) unit used to measure the amount of substance. This quantity is sometimes referred to as the chemical amount. In Latin mole means a "massive heap" of material. It is convenient to think of a chemical mole as such. NOITISOPED
Conceptualizing the Mole Visualizing a mole as a pile of particles, however, is just one way to understand this concept. A sample of a substance has a mass, volume (generally used with gases), and number of particles that is proportional to the chemical amount (measured in moles) of the sample. For example, 1 mole of oxygen gas (O 2) occupies a volume of 22.4 L at standard temperature and pressure (STP; 0°C and 1 atm), has a mass of 31.998 grams, and contains about 6.022 × 10 23 molecules of oxygen.
Mole Definition The mole is the amount of a substance of a system which contains as many elementary entities as there are atoms in 0.012 kilograms (12 AMU) of Carbon. We symbolize this with "mol." When the mole is used, the elementary entities must be specified . 6 x 1023 atoms, 6 x 1023molecules, 6 x 1023ions, 6 x 1023electrons, 6 x 1023particles, or 6 x 1023specified groups of particles.
Math Gives Quantity to the Unseen Atoms and molecules are incredibly small and even a tiny chemical sample contains an unimaginable number of them. Therefore, counting the number of atoms or molecules in a sample is impossible. The multiple interpretations of the mole allow us to bridge the gap between the submicroscopic world of atoms and molecules and the macroscopic world that we can observe.
UCLA researchers have produced microscale particles shaped like each letter of the alphabet. These microscale and nanoscale particles are formed into letters that could be used to 'mark' individual cells or for new medical applications. With the right microscope at home, you could even play Scrabble with these letters…but we couldn’t individually count the number of particles.
Finding Molar Mass Using g/mol To find the molar mass of an element or compound,determine the atomic, molecular, or formula weight (they are all found by using the method below) finding and adding their atomic weights obtained on the periodic table. Express that value in g/mol. Sodium’s molar mass is 22.990 g/mol Chlorine’s molar mass is 35.4527 g/molSodium chloride’s (NaCl) molar mass is 58.443 g/mol and has a formula weight of 58.443 AMU. (atomic mass units)Formaldehyde’s (CH2O) molar mass is 30.03 g/mol and has a molecular weight of 30.03 AMU.
Finding Moles and Particles To find the chemical amount of a sample, chemists measure its mass and divide by its molar mass. Multiplying the chemical amount (in moles) by Avogadro's constant ( 6.02 x 1023) yields the number of particles present in the sample. Example: You have 350g of NaCl. How many moles of NaCl do you have?Sodium chloride’s (NaCl) molar mass is 58.443 g/mol350g NaCl1 Mol NaCl5.99 Mol NaCl 1 58.443 g 1
Avogardo’s Hypothesis Some people think that Amedeo Avogadro (1776–1856) determined the number of particles in a mole and that is why the quantity is known as Avogadro's number. In reality Avogadro built a theoretical foundation for determining accurate atomic and molecular masses. The concept of a mole did not even exist in Avogadro's time.
Relative Size So how about a visual as to the size of 1 mole of something? What if we took ordinary everyday objects that we can easily see such as a drop of water or a penny and all of a sudden had 6.02 x 1023 water drops or pennies? What would a container have to look like to store a mole of water drops or a mole of pennies? Could we even build a container large enough to do it? What do you think?
Avogadro's number of water drops would cover the all of the land in the United States to a depth of roughly 3.3 km (about 2 miles).
Avogadro's number of pennies placed in a rectangular stack roughly 6 meters by 6 meters at the base would stretch for about 9.4 × 10 12 km and extend outside our solar system. It would take light nearly a year to travel from one end of the stack to the other.