The Mole A. Furry Animal B. Beauty mark D. Unit in Chemistry C. Insider Spy

Lab samples contain large numbers of particles which are sometimes to large and inconvenient to work with. Ex. We weigh 1 gram of Magnesium not 530 420 particles of Magnesium!!! Since atoms are too small to count we group them into a unit called the MOLE.

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1 Mole is = 6.02214199 × 1023 particles 602 214 199 000 000 000 000 000 Approx: 602 trillion billion

The Mole A counting unit The mole is exactly the number of atoms in 12 g of carbon 6.022 X 1023 atoms, molecules or formula units

The Mole 1 dozen cookies = 12 cookies 1 mole of cookies = 6.022 X 1023 cookies 1 dozen Al atoms = 12 Al atoms 1 mole of Al atoms = 6.022 X 1023 atoms 1 mole of CO2 = 6.022 x 1023 molecules 1 mole of NaCl = 6.022 x 1023 formula units Note that the NUMBER is always the same, but the MASS is very different!

This number is called Avogadro’s number. Avocado! NOT Amedeo Avogadro (1776-1856) We use the symbol NA to represent Avogadro’s number.

Avogadro’s Number! But Where Did it Come From? It was NOT just picked! It was MEASURED. One of the better methods of measuring this number was the Millikan Oil Drop Experiment Since then we have found even better ways of measuring using x-ray technology

Just How Big is a Mole? Enough soft drink cans to cover the surface of the earth to a depth of over 200 miles. If one mole of pennies was distributed equally among the six billion people on Earth, then each person would have 1 x 1012 dollars. In other words, everyone on earth would be a trillionaire! If we were able to count atoms at the rate of 10 million per second, it would take about 2 billion years to count the atoms in one mole.

A Mole of Particles Contains 6.022 x 1023 particles = 6.022 x 1023 S atoms = 6.022 x 1023 H2O molecules 1 mole S 1 mole H2O

Molar Mass The Mass of 1 mole of a substance (in grams) Equal to the numerical value of the average atomic mass (get from periodic table) Symbol: MM Units: ( g / mol ) 1 mole of C atoms = 12.0 g 1 mole of Mg atoms = 24.3 g 1 mole of Cu atoms = 63.5 g

Learning Check! Determine the Molar Mass of Copper. How many moles is this equal to? How many atoms of copper is this equal to? MMCu = 63.546 g/mol 1 mole 6.022 x 1023 atoms of copper 1 mole = molar mass of the substance = Avogadro’s number

Learning Check! Molar Mass of K2O = ? Grams/mole B. Molar Mass of antacid Al(OH)3 = ? Grams/mole

Learning Check Prozac, C17H18F3NO, is a widely used antidepressant that inhibits the uptake of serotonin by the brain. Find its molar mass.