Chemical Quantities The Mole

Collection Terms A collection term states a specific number of items. 1 dozen donuts = 12 donuts 1 ream of paper = 500 sheets 1 case = 24 cans Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

A Mole of Atoms A mole is a collection that contains the same number of particles as there are carbon atoms in 12.0 g of carbon. 6.02 x 1023 atoms of an element (Avogadro’s number). 1 mole element Number of Atoms 1 mole C = 6.02 x 1023 C atoms 1 mole Na = 6.02 x 1023 Na atoms 1 mole Au = 6.02 x 1023 Au atoms

A Mole of a Compound A mole of a covalent compound has Avogadro’s number of molecules. 1 mole CO2 = 6.02 x 1023 CO2 molecules 1 mole H2O = 6.02 x 1023 H2O molecules of an ionic compound contains Avogadro’s number of formula units. 1 mole NaCl = 6.02 x 1023 NaCl formula units 1 mole K2SO4 = 6.02 x 1023 K2SO4 formula units

Samples of One Mole Quantities 1 mole C = 6.02 x 1023 C atoms 1 mole Al = 6.02 x 1023 Al atoms 1 mole S = 6.02 x 1023 S atoms 1 mole H2O = 6.02 x 1023 H2O molecules 1 mole CCl4 = 6.02 x 1023 CCl4 molecules

Avogadro’s Number Avogadro’s number 6.02 x 1023 can be written as an equality and two conversion factors. Equality: 1 mole = 6.02 x 1023 particles Conversion Factors: 6.02 x 1023 particles and 1 mole 1 mole 6.02 x 1023 particles

Using Avogadro’s Number Avogadro’s number is used to convert moles of a substance to particles. How many Cu atoms are in 0.50 mole Cu? 0.50 mole Cu x 6.02 x 1023 Cu atoms 1 mole Cu = 3.0 x 1023 Cu atoms Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Using Avogadro’s Number Avogadro’s number is used to convert particles of a substance to moles. How many moles of CO2 are in 2.50 x 1024 molecules CO2? 2.50 x 1024 molecules CO2 x 1 mole CO2 6.02 x 1023 molecules CO2 = 4.15 mole CO2

Learning Check 1. The number of atoms in 2.0 mole Al is A. 2.0 Al atoms. B. 3.0 x 1023 Al atoms. C. 1.2 x 1024 Al atoms. 2. The number of moles of S in 1.8 x 1024 atoms S is A. 1.0 mole S atoms. B. 3.0 mole S atoms. C. 1.1 x 1048 mole S atoms.

Solution C. 1.2 x 1024 Al atoms 2.0 mole Al x 6.02 x 1023 Al atoms B. 3.0 mole S atoms 1.8 x 1024 S atoms x 1 mole S 6.02 x 1023 S atoms

Subscripts and Moles The subscripts in a formula show the relationship of atoms in the formula. the moles of each element in 1 mole of compound. Glucose C6H12O6 In 1 molecule: 6 atoms C 12 atoms H 6 atoms O In 1 mole: 6 mole C 12 mole H 6 mole O

Subscripts State Atoms and Moles 9 mole C 8 mole H 4 mole O

Factors from Subscripts The subscripts are used to write conversion factors for moles of each element in 1 mole compound. For aspirin C9H8O4, the following factors can be written: 9 mole C 8 mole H 4 mole O 1 mole C9H8O4 1 mole C9H8O4 1 mole C9H8O4 and 1 mole C9H8O4 1 mole C9H8O4 1 mole C9H8O4 9 mole C 8 mole H 4 mole O

Learning Check A. How many mole O are in 0.150 mole aspirin C9H8O4? B. How many O atoms are in 0.150 mole aspirin C9H8O4?

Solution A. How many mole O are in 0.150 mole aspirin C9H8O4? 0.150 mole C9H8O4 x 4 mole O = 0.600 mole O 1 mole C9H8O4 subscript factor B. How many O atoms are in 0.150 mole aspirin C9H8O4? 0.150 mole C9H8O4 x 4 mole O x 6.02 x 1023 O atoms 1 mole C9H8O4 1 mole O subscript Avogadro’s factor Number = 3.61 x 1023 O atoms

Chapter 10.2 Mole to Mass Relationships Molar Mass

Molar Mass The molar mass is the mass of one mole of an element or compound. is the atomic mass expressed in grams. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

Molar Mass from Periodic Table Molar mass is the atomic mass expressed in grams. 1 mole Ag 1 mole C 1 mole S = 107.9 g = 12.01 g = 32.07 g

Learning Check Give the molar mass for each (to the tenths decimal place). A. 1 mole K atoms = ________ B. 1 mol Sn atoms = ________

Solution Give the molar mass for each (to the tenths decimal place). A. 1 mole K atoms = 39.1 g B. 1 mole Sn atoms = 118.7 g

Molar Mass of a Compound The molar mass of a compound is the sum of the molar masses of the elements in the formula. Example: Calculate the molar mass of CaCl2. Element Number of Moles Atomic Mass Total Mass Ca 1 40.1 g/mole 40.1 g Cl 2 35.5 g/mole 71.0 g CaCl2 111.1 g

Molar Mass of K3PO4 Calculate the molar mass of K3PO4. Element Number of Moles Atomic Mass Total Mass in K3PO4 K 3 39.1 g/mole 117.3 g P 1 31.0 g/mole 31.0 g O 4 16.0 g/mole 64.0 g K3PO4 212.3 g

Some One-mole Quantities 32.1 g 55.9 g 58.5 g 294.2 g 342.2 g

Learning Check What is the molar mass of each of the following? A. K2O B. Al(OH)3

Solution A. K2O 94.2 g/mole 2 mole K (39.1 g/mole) + 1 mole O (16.0 g/mole) 78.2 g + 16.0 g = 94.2 g B. Al(OH)3 78.0 g/mole 1 mole Al (27.0 g/mole) + 3 mol O (16.0 g/mole) + 3 mol H (1.01 g/mole) 27.0 g + 48.0 g + 3.03 g = 78.0 g

Learning Check Prozac, C17H18F3NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? 1) 40.1 g/mole 2) 262 g/mole 3) 309 g/mole

Solution Prozac, C17H18F3NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? 3) 309 g/mole 17 C (12.0) + 18 H (1.01) + 3 F (19.0) + 1 N (14.0) + 1 O (16.0) = 204 + 18.2 + 57.0 + 14.0 + 16.0 = 309 g/mole

Molar Mass Factors Molar mass conversion factors are written from molar mass. relate grams and moles of an element or compound. Example: Write molar mass factors for methane, CH4, used in gas stoves and gas heaters. Molar mass: 1 mol CH4 = 16.0 g Conversion factors: 16.0 g CH4 and 1 mole CH4 1 mole CH4 16.0 g CH4

Learning Check Acetic acid C2H4O2 gives the sour taste to vinegar. Write two molar mass conversion factors for acetic acid.

Solution Acetic acid C2H4O2 gives the sour taste to vinegar. Write two molar mass factors for acetic acid. Calculate molar mass: 24.0 + 4.04 + 32.0 = 60.0 g/mole 1 mole of acetic acid = 60.0 g acetic acid Molar mass factors 1 mole acetic acid and 60.0 g acetic acid 60.0 g acetic acid 1 mole acetic acid

Calculations Using Molar Mass Molar mass factors are used to convert between the grams of a substance and the number of moles. Molar mass factor Moles Grams

Moles to Grams Aluminum is often used to build lightweight bicycle frames. How many grams of Al are in 3.00 mole Al? Molar mass equality: 1 mole Al = 27.0 g Al Setup with molar mass as a factor: 3.00 mole Al x 27.0 g Al = 81.0 g Al 1 mole Al molar mass factor for Al

Learning Check Allyl sulfide C6H10S is a compound that has the odor of garlic. How many moles of C6H10S are in 225 g?

Solution Calculate the molar mass of C6H10S. (6 x 12.0) + (10 x 1.01) + (1 x 32.1) = 114.2 g/mole Set up the calculation using a mole factor. 225 g C6H10S x 1 mole C6H10S 114.2 g C6H10S molar mass factor (inverted) = 1.97 mole C6H10S

Grams, Moles, and Particles A molar mass factor and Avogadro’s number convert grams to particles. molar mass Avogadro’s number g mole particles particles to grams. Avogadro’s molar mass particles mole g

Learning Check How many H2O molecules are in 24.0 g H2O? 1) 4.52 x 1023 2) 1.44 x 1025 3) 8.03 x 1023

Solution How many H2O molecules are in 24.0 g H2O? 3) 8.02 x 1023 24.0 g H2O x 1 mole H2O x 6.02 x 1023 H2O molecules 18.0 g H2O 1 mole H2O = 8.03 x 1023 H2O molecules

Learning Check If the odor of C6H10S can be detected from 2 x 10-13 g in one liter of air, how many molecules of C6H10S are present?

Solution If the odor of C6H10S can be detected from 2 x 10-13 g in one liter of air, how many molecules of C6H10S are present? 2 x 10-13 g x 1 mole x 6.02 x 1023 molecules 114.2 g 1 mole = 1 x 109 molecules C6H10S

Volume and Moles (Avogadro’s Law) Chapter 10.2 Mole to Volume Volume and Moles (Avogadro’s Law)

Avogadro's Law: Volume and Moles In Avogadro’s Law the volume of a gas is directly related to the number of moles (n) of gas. T and P are constant.

STP The volumes of gases can be compared at STP, Standard Temperature and Pressure, when they have the same temperature. Standard temperature (T) 0°C or 273 K the same pressure. Standard pressure (P) 1 atm (760 mm Hg)

Molar Volume At standard temperature and pressure (STP), 1 mole of a gas occupies a volume of 22.4 L, which is called its molar volume.

Molar Volume as a Conversion Factor The molar volume at STP can be used to form conversion factors. 22.4 L and 1 mole 1 mole 22.4 L

Using Molar Volume What is the volume occupied by 2.75 moles N2 gas at STP? The molar volume is used to convert moles to liters. 2.75 moles N2 x 22.4 L = 61.6 L 1 mole

Guide to Using Molar Volume

Learning Check A. What is the volume at STP of 4.00 g of CH4? 1) 5.60 L 2) 11.2 L 3) 44.8 L B. How many grams of He are present in 8.00 L of gas at STP? 1) 25.6 g 2) 0.357 g 3) 1.43 g