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Moles. Chapter 10. The Mole. A number of atoms, ions, or molecules that is large enough to see and handle. A mole = number of things Just like a dozen = 12 things One mole = 6.022 x 10 23 things Avogadro’s constant = 6.022 x 10 23 Symbol for Avogadro’s constant is N A. The Mole.
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Moles • Chapter 10
The Mole • A number of atoms, ions, or molecules that is large enough to see and handle. • A mole = number of things • Just like a dozen = 12 things • One mole = 6.022 x 1023 things • Avogadro’s constant = 6.022 x 1023 • Symbol for Avogadro’s constant is NA.
The Mole • How do we know when we have a mole? • count it out • weigh it out • Molar mass - mass in grams numerically equal to the atomic weight of the element in grams. • H has an atomic weight of 1.00794 g • 1.00794 g of H atoms = 6.022 x 1023 H atoms • Mg has an atomic weight of 24.3050 g • 24.3050 g of Mg atoms = 6.022 x 1023 Mg atoms
The Mole • Example 2-1: Calculate the mass of a single Mg atom in grams to 3 significant figures.
The Mole • Example 2-1: Calculate the mass of a single Mg atom in grams to 3 significant figures.
The Mole • Example 2-1: Calculate the mass of a single Mg atom in grams to 3 significant figures.
The Mole • Example 2-1: Calculate the mass of a single Mg atom, in grams, to 3 significant figures.
The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.
The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.
The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.
The Mole • Example 2-2: Calculate the number of atoms in one-millionth of a gram of Mg to 3 significant figures.
The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?
The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?
The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?
The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?
The Mole • Example 2-3. How many atoms are contained in 1.67 moles of Mg?
The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg? You do it!
The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg?
The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg?
The Mole • Example 2-4: How many moles of Mg atoms are present in 73.4 g of Mg? IT IS IMPERATIVE THAT YOU KNOW HOW TO DO THESE PROBLEMS
Formula Weights, Molecular Weights, and Moles • How do we calculate the molar mass of a compound? • add atomic weights of each atom • The molar mass of propane, C3H8, is: • 3C X 12.01g = 36.03g • 8H X 1.01 g = 8.08g • 44.11g /mole
Formula Weights, Molecular Weights, and Moles • The molar mass of calcium nitrate, Ca(NO3)2 , is: You do it!
Formula Weights, Molecular Weights, and Moles • One Mole of Contains • Cl2 or 70.90g 6.022 x 1023 Cl2 molecules 2(6.022 x 1023 ) Cl atoms • C3H8You do it!
Formula Weights, Molecular Weights, and Moles • One Mole of Contains • Cl2 or 70.90g 6.022 x 1023 Cl2 molecules 2(6.022 x 1023 ) Cl atoms • C3H8 or44.11 g 6.022 x 1023 C3H8 molecules 3 (6.022 x 1023 ) C atoms 8 (6.022 x 1023 ) H atoms
Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.
Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.
Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.
Formula Weights, Molecular Weights, and Moles • Example 2-5: Calculate the number of C3H8 molecules in 74.6 g of propane.
Formula Weights, Molecular Weights, and Moles • Example 2-6. What is the mass of 10.0 billion propane molecules? You do it!
Formula Weights, Molecular Weights, and Moles • Example 2-6. What is the mass of 10.0 billion propane molecules?
Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. You do it!
Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. (a)
Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. (b)
Formula Weights, Molecular Weights, and Moles • Example 2-7. How many (a) moles, (b) molecules, and (c) oxygen atoms are contained in 60.0 g of ozone, O3? The layer of ozone in the stratosphere is very beneficial to life on earth. (c)
Formula Weights, Molecular Weights, and Moles • Example 2-8. Calculate the number of O atoms in 26.5 g of Li2CO3. You do it!
Formula Weights, Molecular Weights, and Moles • Example 2-8. Calculate the number of O atoms in 26.5 g of Li2CO3.
Percent Composition and Formulas of Compounds • % composition = mass of an individual element in a compound divided by the total mass of the compound x 100% • Determine the percent composition of C in C3H8.
Percent Composition and Formulas of Compounds • What is the percent composition of H in C3H8? You do it!
Percent Composition and Formulas of Compounds • What is the percent composition of H in C3H8?
Percent Composition and Formulas of Compounds • Example 2-10: Calculate the percent composition of Fe2(SO4)3 to 3 significant figures. You do it!
Percent Composition and Formulas of Compounds • Example 2-10: Calculate the percent composition of Fe2(SO4)3 to 3 sig. fig.
Derivation of Formulas from Elemental Composition • Example 2-11: A compound contains 24.74% K, 34.76% Mn, and 40.50% O by mass. What is its empirical formula? • Make the simplifying assumption that we have 100.0 g of compound. • In 100.0 g of compound there are: • 24.74 g of K • 34.76 g of Mn • 40.50 g of O
Derivation of Formulas from Elemental Composition • Example 2-12: A sample of a compound contains 6.541g of Co and 2.368g of O. What is the empirical formula for this compound? You do it!
Derivation of Formulas from Elemental Composition • Example 2-12: A sample of a compound contains 6.541g of Co and 2.368g of O. What is the empirical formula for this compound?
Derivation of Formulas from Elemental Composition • Example 2-12: A sample of a compound contains 6.541g of Co and 2.368g of O. What is the empirical formula for this compound?