Unit 6 The Mole Formula Mass Formula mass

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Unit 6 The Mole

Unit 6 The Mole

Formula Mass Formula mass – the sum of the average atomic masses of all

Formula Mass Formula mass – the sum of the average atomic masses of all the atoms in the formula (ionic) unit is amu Molecular mass – the sum of the average atomic masses of all the atoms in a molecule (covalent) unit is amu ***Remember*** A molecule is a neutral group of atoms that are held together by covalent bonds

Counting Particles A dozen means…? 12 A pair means…? 2 A ream of paper

Counting Particles A dozen means…? 12 A pair means…? 2 A ream of paper is 500 sheets Regardless of the object, the counting unit always means the same number Chemists use a constant counting unit to count atoms, molecules, and formula units

The Mole – the SI base unit used to measure the amount of a

The Mole – the SI base unit used to measure the amount of a substance (mol) A number “equal to the number of carbon atoms in exactly 12 g of pure carbon-12” A mole of anything contains 6. 02 x 1023 representative particles (Avogadro’s number)

Avogadro’s Number 602, 213, 670, 000, 000 That’s a big number!

Avogadro’s Number 602, 213, 670, 000, 000 That’s a big number!

Molar Mass Molar mass – the mass of one mole of a pure substance

Molar Mass Molar mass – the mass of one mole of a pure substance in g/mol– equal to the atomic mass (atoms) the formula mass (for ionic compounds) or molecular mass (for molecules) Just change the units from amu to g/mol Ex: Find the molar mass of Iron 55. 845 g/mol

Molar Mass For ionic compounds or molecules: 1. multiply the number of each atom

Molar Mass For ionic compounds or molecules: 1. multiply the number of each atom in the substance by the atoms atomic mass 2. Add the numbers for all of the atoms together to get the molar mass in g/mol

Molar Mass What is the molar mass of KCl? number of K atoms ___

Molar Mass What is the molar mass of KCl? number of K atoms ___ x mass of K _____ = _______ number of Cl atoms ___ x mass of Cl ______ = _______ total mass of K + total mass of Cl = ____

 What is the molar mass of KCl? number of K atoms 1 x

What is the molar mass of KCl? number of K atoms 1 x mass of K 39. 098 = 39. 098 number of Cl atoms 1 x mass of Cl 35. 453 = 35. 453 total mass of K + total mass of Cl = 74. 551 g/mol

 What is the molar mass of Ba(NO 3)2? number of Ba atoms ____

What is the molar mass of Ba(NO 3)2? number of Ba atoms ____ x mass of Ba _____ = _______ number of N atoms ____ x mass of N _____ = _______ number of O atoms ____ x mass of O _____ = _______ total mass of Ba + total mass of N + total mass of O = _______

 What is the molar mass of Ba(NO 3)2? number of Ba atoms _1_

What is the molar mass of Ba(NO 3)2? number of Ba atoms _1_ x mass of Ba _137. 328__ = __ 137. 328 __ number of N atoms _2__ x mass of N __ 14. 007__ = __ 28. 01 4_ number of O atoms __6__ x mass of O _ 15. 999_ = __95. 994___ total mass of Ba + total mass of N + total mass of O = (137. 328 + 28. 014 + 95. 994) = 261. 336 g/mol

Mole Conversions Grams Moles Grams 1. 2. 3. 4. Calculate the molar mass Set

Mole Conversions Grams Moles Grams 1. 2. 3. 4. Calculate the molar mass Set up a picket fence Put what you’re given in the top left corner of the picket fence Place the molar mass on the picket fence so that the units cancel

 How many moles are in 67. 42 g Si? 1. molar mass Si

How many moles are in 67. 42 g Si? 1. molar mass Si = 28. 086 g/mol 2. 3. 67. 43 g Si 4. 67. 43 g Si 1 mole 28. 086 g = 2. 403 mol

Mole Conversions How many moles are in 28. 8 g Br 2? 1. Molar

Mole Conversions How many moles are in 28. 8 g Br 2? 1. Molar Mass: 159. 808 g/mol 2. (draw picket fence) 3. 28. 8 g Br 2 4. 28. 8 g Br 2 1 mole 159. 808 g = 0. 180 mol

Mole Conversions How many grams are in 7. 8 mol of Zn. SO 4?

Mole Conversions How many grams are in 7. 8 mol of Zn. SO 4? 1. Molar Mass = 161. 442 g/mol 2. (draw picket fence) 3. 7. 8 mol 4. 7. 8 mol 161. 442 g 1 mol = 1259. 248 g

Mole Conversions How many atoms are in 0. 30 mol F 2?

Mole Conversions How many atoms are in 0. 30 mol F 2?

Mole Conversions How many molecules are in 2. 9 mol NH 3?

Mole Conversions How many molecules are in 2. 9 mol NH 3?

Mole Conversions How many moles are in 3. 5 x 1024 molecules of H

Mole Conversions How many moles are in 3. 5 x 1024 molecules of H 2 O?

Mole Conversions How many moles are in 5. 7 x 1025 molecules of potassium

Mole Conversions How many moles are in 5. 7 x 1025 molecules of potassium iodide?

Mole Conversions What is the mass in 15 grams of 7. 5 x 10

Mole Conversions What is the mass in 15 grams of 7. 5 x 10 atoms of nickel?

Mole Conversions How many molecules are in 65. 3 g of sulfuric acid?

Mole Conversions How many molecules are in 65. 3 g of sulfuric acid?

Percent Composition What is the percent composition of each element in KMn. O 4?

Percent Composition What is the percent composition of each element in KMn. O 4?

Mole Conversions How many bromide ions are in 16. 9 g of Ca. Br

Mole Conversions How many bromide ions are in 16. 9 g of Ca. Br 2?

Mole Conversions How many sodium ions are in 12. 5 g of Na 2

Mole Conversions How many sodium ions are in 12. 5 g of Na 2 SO 4?

Empirical Formulas Empirical formula – the symbols for the elements combined in a compound

Empirical Formulas Empirical formula – the symbols for the elements combined in a compound with subscripts showing the smallest wholenumber mole ratio of the different atoms in a compound

Empirical Formulas The percent composition of a compound contains 78. 1% boron and 21.

Empirical Formulas The percent composition of a compound contains 78. 1% boron and 21. 9% hydrogen. What is the empirical formula?

Empirical Formulas What’s the empirical formula of a molecule containing 18. 7% lithium, 16.

Empirical Formulas What’s the empirical formula of a molecule containing 18. 7% lithium, 16. 3% carbon, and 65. 0% oxygen?

Empirical Formulas Write the molecular formula for a compound with an empirical formula of

Empirical Formulas Write the molecular formula for a compound with an empirical formula of P 2 O 5 and a formula mass of 284 amu.

Empirical Formulas Write the molecular formula for a compound with an empirical formula of

Empirical Formulas Write the molecular formula for a compound with an empirical formula of CH and a formula mass of 78 amu.