1 Chapter 7 Chemical Quantities The Mole Basic Chemistry Copyright © 2011 Pearson Education, Inc....

1

Chapter 7 Chemical Quantities

The Mole

Basic Chemistry Copyright © 2011 Pearson Education, Inc.

Collections of items include dozen, gross, and mole.

2

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


Collections of items include dozen, gross, and mole.

3

A mole (mol) is a collection that contains

• the same number of particles as there are carbon atoms in 12.01 g of carbon.

• 6.022 x 1023 atoms of an element (Avogadro’s number).

1 mol of Element Number of Atoms

1 mol C = 6.022 x 1023 C atoms

1 mol Na = 6.022 x 1023 Na atoms

1 mol Au = 6.022 x 1023 Au atoms

A Mole of Atoms


4

A mole

• of a covalent compound has Avogadro’s number of molecules

1 mol CO2 = 6.022 x 1023 CO2 molecules

1 mol H2O = 6.022 x 1023 H2O molecules

• of an ionic compound contains Avogadro’s number of formula units

1 mol NaCl = 6.022 x 1023 NaCl formula units

1 mol K2SO4 = 6.022 x 1023 K2SO4 formula units

A Mole of A Compound


5

Samples of One Mole Quantities


6

Avogadro’s number (6.022 x 1023) can be written as an equality and two conversion factors.

Equality:

1 mol = 6.022 x 1023 particles

Conversion Factors:

6.022 x 1023 particles and 1 mol 1 mol 6.022 x 1023

particles

Avogadro’s Number


7

Using Avogadro’s Number

Avogadro’s number converts moles of a substance to the number of particles.

How many Cu atoms are in 0.50 mol of Cu?

0.50 mol Cu x 6.022 x 1023 Cu atoms

1 mol Cu

= 3.0 x 1023 Cu atoms


8

Using Avogadro’s Number

Avogadro’s number is used to convert the number of particles of a substance to moles.

How many moles of CO2 are in 2.50 x 1024 molecules of CO2?

2.50 x 1024 molecules CO2

x 1 mol CO2

6.022 x 1023 molecules CO2

= 4.15 mol of CO2


9

1. The number of atoms in 2.0 mol of 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 of S is

A. 1.0 mol of S atoms

B. 3.0 mol of S atoms

C. 1.1 x 1048 mol of S atoms

Learning Check


10

1. 2.0 mol Al x 6.022 x 1023 Al atoms

1 mol Al

= 1.2 x 1024 Al atoms (C)

2. 1.8 x 1024 S atoms x 1 mol S

6.022 x 1023 S atoms = 3.0 mol of S atoms (B)

Solution


11

Subscripts and Moles

The subscripts in a formula state• the relationship of atoms in the formula• the moles of each element in 1 mol of compound

Glucose

C6H12O6

1 molecule: 6 atoms of C 12 atoms of H 6 atoms of O

1 mol: 6 mol of C 12 mol of H 6 mol of O


12

Subscripts State Atoms and Moles


13

Factors from Subscripts

Subscripts used for conversion factors• relate moles of each element in 1 mol of compound • for aspirin C9H8O4 can be written as

9 mol C 8 mol H 4 mol O

1 mol C9H8O4 1 mol C9H8O4 1 mol C9H8O4

and

1 mol C9H8O4 1 mol C9H8O4 1 mol C9H8O4

9 mol C 8 mol H 4 mol O


Calculating Atoms or Molecules

14 Basic Chemistry Copyright © 2011 Pearson Education, Inc.

15

Learning Check

How many O atoms are in 0.150 mol of aspirin, C9H8O4?


16

Solution

How many O atoms are in 0.150 mol of aspirin, C9H8O4?

STEP 1 Given 0.150 mol of C9H8O4

Need molecules of C9H8O4

STEP 2 Plan

moles of aspirin moles of O atoms of O


17

Solution (continued)STEP 3 Equalities/Conversion Factors

1 mol of C9H8O4 = 4 mol of O

1 mol C9H8O4 and 4 mol O

4 mol O 1 mol C9H8O4

1 mol of O = 6.022 x 1023 atoms of O

1 mole O and 6.022 x 1023 atoms O

6.022 x 1023 atoms O 1 mol O

STEP 4 Set Up Problem

0.150 mol C9H8O4 x 4 mol O x 6.022 x 1023 O atoms

1 mol C9H8O4 1 mol O

= 3.61 x 1023 O atoms


18

Molar Mass


Lithium carbonate produces a red color in fireworks.

19

Molar Mass

The molar mass • is the mass of one mol of an

element or compound• is the atomic mass expressed in

grams


20

Molar Mass from the Periodic Table


21

Give the molar mass for

A. 1 mol of K atoms = ________

B. 1 mol of Sn atoms = ________

Learning Check


22

Give the molar mass for

A. 1 mol of K atoms = 39.10 g

B. 1 mol of Sn atoms = 118.7 g

Solution


Guide to Calculating Molar mass

23 Basic Chemistry Copyright © 2011 Pearson Education, Inc.

24

Molar Mass of a Compound

For a compound, the molar mass 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 40.08 g/mol 40.08 g

Cl 2 35.45 g/mol 70.90 g

CaCl2 110.98 g


25

Molar Mass of K3PO4

Determine the molar mass of K3PO4.

Element Number of Moles

Atomic Mass Total Mass in K3PO4

K 3 39.10 g/mol 117.3 g

P 1 30.97 g/mol 30.97 g

O 4 16.00 g/mol 64.00 g

K3PO4 212.3 g


26

Some One-Mol Quantities


27

Calculate the molar mass for Al(OH)3 with four

significant figures.

1) 44.00 g/mol

2) 75.00 g/mol

3) 78.00 g/mol

Learning Check


28

STEP 1 Obtain the molar mass of each element. Al 26.98 g/mol O 16.00 g/mol H 1.008 g/molSTEP 2 Multiply each by the subscript.

1 mol Al x 26.98 g Al = 26.98 g 1 mol Al

3 mol O x 16.00 g O = 48.00 g 1 mol O

3 mol H x 1.008 g H = 3.024 g

1 mol H STEP 3 Calculate the molar mass by adding the

masses of the elements. 1 mol of Al(OH)3 = 78.00 g (3)

Solution


29

Prozac, C17H18F3NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac?1) 40.06 g/mol2) 262.0 g/mol 3) 309.4 g/mol

Learning Check


30

Prozac, C17H18F3NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac?

STEP 1 Obtain the molar mass of each element. C 12.01 g/mol H 1.008 g/mol F 19.00 g/mol N 14.01 g/mol O 16.00 g/mol

STEP 2 Multiply each by the subscript in the formula. 17 mol C x 12.01 g C = 204.2 g

1 mol C 18 mol H x 1.008 g H = 18.14 g

1 mol H

Solution


Solution (continued)

STEP 2 3 mol F x 19.00 g F = 57.00 g

1 mol F 1 mol N x 14.01 g N = 14.01 g 1 mol N

1 mol O x 16.00 g O = 16.00 g

1 mol O

STEP 3 1 mol of C17H18F3NO = 309.4 g

31

32

Calculations Using Molar Mass

Calculations Using Molar Mass


Table salt is NaCl.

33

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 cook tops and gas heaters.

Molar mass:

1 mol CH4 = 16.04 g

Conversion factors:

16.04 g CH4 and 1 mol CH4

1 mol CH4 16.04 g CH4

Molar Mass Factors


34

Acetic acid HC2H3O2 gives the sour taste to vinegar. Write an equality and two molar mass conversion factors for acetic acid.

Learning Check


35

Acetic acid HC2H3O2 gives the sour taste to vinegar.Write an equality and two molar mass conversion

factors for acetic acid.

Equality:

1 mol of acetic acid = 60.05 g of acetic acid

Molar mass conversion factors:

1 mol acetic acid and 60.05 g acetic acid 60.05 g acetic acid 1 mol acetic acid

Solution


36

Guide to Calculation Using Molar Mass


37

Aluminum is used to build lightweight bicycleframes. How many grams of Al are in 3.00 mol of Al?

Moles to Grams


38

STEP 1 Given 3.00 mol of Al Need grams of Al

STEP 2 Plan moles of Al grams of Al

STEP 3 Equalities/Conversion Factors

1 mol of Al = 26.98 g of Al 1 mol Al and 26.98 g Al

26.98 g Al 1 mol Al

Solution


39

STEP 4 Set Up ProblemSet up with molar mass as a factor:

3.00 mol Al x 26.98 g Al = 80.9 g of Al 1 mol Al molar mass factor for Al



40

The artificial sweetener aspartame (NutraSweet), C14H18N2O5, is used to sweeten diet foods, coffee, and soft drinks. How many moles of aspartame are present in 225 g of aspartame?

Learning Check


41

STEP 1 Given 225 g of C14H18N2O5 Need molesSTEP 2 Plan g of aspartame moles of aspartameSTEP 3 Equalities/Conversion Factors

1 mol aspartame = 294.3 g 1 mol aspartame and 294.3 g aspartame 294.3 g aspartame 1 mol aspartameSTEP 4 Set Up Problem

225 g aspartame x 1 mol aspartame 294.3 g aspartame

mole factor (inverted)

= 0.765 mol of aspartame

Solution


42

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


43

STEP 1 Given 225 g of C6H10S Need moles of C6H10S

STEP 2 Plan g of C6H10S moles of C6H10S


1 mol of C6H10S = 114.21 g of C6H10S

1 mol C6H10S and 114.21 g C6H10S

114.21 g C6H10S 1 mol C6H10S

STEP 3 Set Up Problem 225 g C6H10S x 1 mol C6H10S

114.21 g C6H10S

= 1.97 mol C6H10S

Solution


Guide to Converting Grams to Particles

44

45

Learning Check

How many molecules of H2O are in 24.0 g of H2O?

1) 4.52 x 1023

2) 1.44 x 1025

3) 8.02 x 1023


46

Solution

STEP 1 Given 24.0 g of H2O

Need molecules of H2O

STEP 2 Plan

g of H2O moles of H2O molecules of H2O


1 mol of H2O = 18.02 g of H2O

1 mol H2O and 18.02 g H2O

18.02 g H2O 1 mol H2O


47


STEP 3 Equalities/Conversion Factors (continued)

1 mol of H2O = 6.022 molecules of H2O

1 mol H2O and 6.022 x 1023 H2O molecules

6.022 H2O molecules 1 mol H2O

STEP 4 Set Up Problem

24.0 g H2O x 1 mol H2O

18.02 g H2O

x 6.022 x 1023 H2O molecules

1 mol H2O

= 8.02 x 1023 H2O molecules (3)


1 Chapter 7 Chemical Quantities The Mole Basic Chemistry Copyright © 2011 Pearson Education, Inc....

Documents

Transcript of 1 Chapter 7 Chemical Quantities The Mole Basic Chemistry Copyright © 2011 Pearson Education, Inc....