Unit 7: The Mole

Measuring Matter What are three methods for measuring the amount of something? You often measure the amount of something by one of three different methods—by count, by mass, and by volume. We use all 3 in chemistry.

Converting from Count to Mass Converting Number of Donuts to a Dozen: 1 dozen = 12 donuts

What is a Mole? 1 mole of any substance = 6.02  1023 particles (Avogadro’s number of particles) 602,000,000,000,000,000,000,000 - Particles can be atoms, molecules, or formula units. http://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one#review

What is a Mole?

Molar Mass v. Atomic Mass Mass of 1 atom Mass of 1 mole = mass of 6.02 x 1023 atoms Atomic Mass (amu) Molar Mass (g/mol) 1 atom of Carbon 1 mole of Carbon 12.0 amu 12.0 g

The Definition of the Mole Avogadro defined the mole: One mole, 6.02  1023 particles, is exactly 12.0 g of Carbon-12 The carbon-12 isotope is used as the standard for both amu and the mole.

Molar Mass of a Compound The molar mass is the sum of the atomic mass of each element in the compound. MgCl2 # atoms atomic mass total mass Mg 1 24.3 24.3 Cl 2 35.5 +71.0 Molar Mass: 1 mole MgCl2 = 95.3 g

Practice Calculate the molar mass of the following: KOH HCl H2SO4 C2H6 (39.1x1) + (16.0x1) + (1.0x1) = 56.1 g/mol (1.0x1) + (35.5x1) = 36.5 g/mol (1.0x2) + (32.1x1) + (16.0x4) = 98.1 g/mol (12.0x2) + (1.0x6) = 30.0 g/mol

Mole Conversions 1 mole = 6.02  1023 particles 1 mole = _______ g *particles could be molecules, ions, atoms, formula units 1 mole = _______ g *1 mole equals the molar mass of the atom or compound 1 mole = 22.4 L * for gases only at STP (Standard Temperature (0˚C and Standard Pressure (1 atm))

MOLE CONVERSIONS How many moles is 350 g CO? Molar Mass: 1 mole = (12.0x1) + (16.0x1) = 28.0 g = 12.5 moles CO 350 g CO 1 mol CO 28.0 g CO What is the volume of 0.05 mol Ne at STP? = 1.12 L Ne 0.05 mol Ne 22.4 L 1 mol

Multiplying and Dividing Scientific Notation: Multiplying exponents: Multiply coefficients and add exponents: (1x106) x (1x105) = 1x1011 Dividing exponents: Divide coefficients and subtract exponents: (1x108) ÷ (1x1016) = 1x10-8

Using your calculator for Scientific Notation: To enter a number in scientific notation on your calculator use the EE or x10y or EXP button. Example: 6.02 x 1023 enter 6.02 EE 23 [or 6.02 x10y 23]

Using your calculator: Practice: Example: (1.2 x 103) x (6.02 x 1023) enter 1.2 EE 3 x 6.02 EE 23 = [1.2 x10y 3 x 6.02 x10y 23 =] = 7.2 x 1026 CHECK exponents: 3 + 23 = 26

Using your calculator: Practice: Example: (4.9 x 109) x (6.02 x 1023) enter 4.9 EE 9 x 6.02 EE 23 = [4.9 x10y 9 x 6.02 x10y 23 =] = 2.9 x 1033 CHECK exponents: 9 + 23 = 32

Using your calculator: Practice: Example: (1.20 x 1024) ÷ (6.02 x 1023) enter 1.20 EE 24 ÷ 6.02 EE 23 = [1.20 x10y 24 ÷ 6.02 x10y 23 =] = 1.99 x 100 = 1.99 CHECK exponents: 24 - 23 = 1

Using your calculator: Practice: Example: (3.7 x 1063) ÷ (6.02 x 1023) enter 3.7 EE 63 ÷ 6.02 EE 23 = [3.7 x10y 63 ÷ 6.02 x10y 23 =] = 6.2 x 1039 CHECK exponents: 63 - 23 = 40

Mole Conversions How many moles is 2.17 x 1023 particles? 1 mole =6.02  1023 particles = 0.36 x 100 = 0.36 moles 2.17 x 1023 particles 1 mole 6.02 x 1023 particles

Mole Conversions How many particles is 15 moles? 1 mole =6.02  1023 particles = 9.03 x 1024 particles 15 moles 6.02 x 1023 particles 1 mole

Mole Conversions Convert 14 g N2 to number of molecules: Identify the conversion factors: 1 mole = _______________ g 1 mole = 6.02 x 1023 molecules = 3.01 x 1023 molecules N2 (14.0x2) = 28.0 14 g N2 1 mole 6.02 x 1023 molecules 28.0 g N2

Mole Conversions Convert 9.4x1025 molecules of H2 to grams: First identify the conversion factors: 1 mole = ______________________ g 1 mole = 6.02 x 1023 molecules 2. Draw a 2-step “T” chart: = 312 g H2 (1.0g x 2) = 2.0 9.4x1025 molecules 1 mole 2.0 g H2 6.02 x 1023 molecules

Mole Conversions 1 mole = 6.02  1023 particles 1 mole = _______ g *particles could be molecules, ions, atoms, formula units 1 mole = _______ g *1 mole equals the molar mass of the atom or compound 1 mole = 22.4 L * for gases only at STP (Standard Temperature (0˚C and Standard Pressure (1 atm))

atoms, ions, molecules, formula units MOLE CONVERSIONS Molar Mass (g) Volume in Liters Particles: atoms, ions, molecules, formula units Mass in grams particles = = 1 =