Chapter 04

# Chapter 04 - Chapter 3 The Mole: Connecting the Macroscopic...

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Chapter 3 The Mole: Connecting the Macroscopic and Molecular Worlds Stoichiometry From the Greek words stoicheioin element Metron measure Concerned with the ratios by atoms of the elements in compounds Use large scale measurements to count tiny objects Manufacture on small and large scales – figure 4.1 example of counting coins easy to count a pocket full difficult to count a bucketful what if you knew the mass of one coin? Count atoms in a mass of element using atomic masses Example 4.1 How many atoms of copper are in 10.0 kg of copper? Chem 111 Lecture Notes By Alan Zombeck page 1

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Chapter 3 Mass measurements can be used to count molecules using molecular mass Example 4.2 What is the molecular mass of dimethyl sulfide (CH 3 ) 2 S? The mole conveniently links mass to number of atoms or molecules Avogadro’s Number and the Mole Mole one mole of any element or compound has the same number of formula units as there are atoms in exactly 12 g of carbon-12 The story of Avogadro 1 mole = 6.02 x 10 23 of things doesn’t matter if things= atoms, compounds, ions, pizzas, etc…. . Hint; think of a mole as a quantity containing 6.02 x 10 23 of items, just like a dozen eggs contains 12 eggs Something to think about This illustrates how small atoms/molecules are!!!! Chem 111 Lecture Notes By Alan Zombeck page 2 1 mole of \$ would provide everyone in the world with an income of \$3 Million per second for 100 years.
Chapter 3 Example 4.4 If a fuel pellet contained 0.880 g of Pu-238, how many moles of Pu-238 were in the fuel pellet? Example 4.5 The human body loses about 0.010 mol of potassium daily in the urine, with larger losses in the stool. How many grams of potassium are lost each day in the urine? Example 4.6 Bone and dental implants are often coated with calcium phosphate Ca 3 (PO 4 ) 2 , to permit bone to bond with the implant surface. If a coating procedure can deposit 0.115 mol of pure Ca 3 (PO 4 ) 2 on an implant, how many grams does the coating weigh? Example 4.7 How many atoms are in a particle of plutonium that contains 1.00 x 10 -6 (1.00 μg) of plutonium-239? Chem 111 Lecture Notes By Alan Zombeck page 3

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Chapter 3 Chemical formulas relate amounts of substances in a compound The stoichiometric equivalence of two elements in a chemical formula is the ratio (by atoms or moles) in which they occur in the formula. Example H 2 O formula tells us there are 2 hydrogen atoms and 1 oxygen atom in the molecule formula also tells us there are 2 moles of hydrogen atoms and 1 mole of oxygen atoms in 1 mole of water molecules Measuring moles of elements and compounds One mole of any element has a mass in grams that is numerically equal to the element’s atomic mass Using Avogadro’s number in calculations We can calculate any of the following, if we know one of them
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## This note was uploaded on 04/28/2008 for the course CHEM 111 taught by Professor Zombeck during the Winter '07 term at Saginaw Valley.

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Chapter 04 - Chapter 3 The Mole: Connecting the Macroscopic...

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