Chapter 7 Chemical Quantities

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1 Chapter 7 Chemical Quantities The Mole Collections of items include dozen, gross, and mole. 1

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. 2

3 A Mole of Atoms A mole (mol) is a collection that contains the same number of particles as there are carbon atoms in g of carbon x atoms of an element (Avogadro s number). 1 mol of Element Number of Atoms 1 mol C = x C atoms 1 mol Na = x Na atoms 1 mol Au = x Au atoms 3

4 A Mole of A Compound A mole of a covalent compound has Avogadro s number of molecules 1 mol CO 2 = x CO 2 molecules 1 mol H 2 O = x H 2 O molecules of an ionic compound contains Avogadro s number of formula units 1 mol NaCl = x NaCl formula units 1 mol K 2 SO 4 = x K 2 SO 4 formula units 4

5 Samples of One Mole Quantities 5

6 Avogadro s Number Avogadro s number (6.022 x ) can be written as an equality and two conversion factors. Equality: 1 mol = x particles Conversion Factors: x particles and 1 mol 1 mol x particles 6

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 x Cu atoms 1 mol Cu = 3.0 x Cu atoms 7

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 CO 2 are in 2.50 x molecules of CO 2? 2.50 x molecules CO 2 x 1 mol CO x molecules CO 2 = 4.15 mol of CO 2 8

9 Learning Check 1. The number of atoms in 2.0 mol of Al is A. 2.0 Al atoms B. 3.0 x Al atoms C. 1.2 x Al atoms 2. The number of moles of S in 1.8 x atoms of S is A. 1.0 mol of S atoms B. 3.0 mol of S atoms C. 1.1 x mol of S atoms 9

10 Solution mol Al x x Al atoms 1 mol Al = 1.2 x Al atoms (C) x S atoms x 1 mol S x S atoms = 3.0 mol of S atoms (B) 10

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 C 6 H 12 O 6 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 11

12 Subscripts State Atoms and Moles 12

13 Factors from Subscripts Subscripts used for conversion factors relate moles of each element in 1 mol of compound for aspirin C 9 H 8 O 4 can be written as 9 mol C 8 mol H 4 mol O 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 and 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 9 mol C 8 mol H 4 mol O 13

14 Calculating Atoms or Molecules 14

15 Learning Check How many O atoms are in mol of aspirin, C 9 H 8 O 4? 15

16 Solution How many O atoms are in mol of aspirin, C 9 H 8 O 4? STEP 1 Given mol of C 9 H 8 O 4 Need molecules of C 9 H 8 O 4 STEP 2 Plan moles of aspirin moles of O atoms of O 16

17 Solution (continued) STEP 3 Equalities/Conversion Factors 17 1 mol of C 9 H 8 O 4 = 4 mol of O 1 mol C 9 H 8 O 4 and 4 mol O 4 mol O 1 mol C 9 H 8 O 4 1 mol of O = x atoms of O 1 mole O and x atoms O x atoms O 1 mol O STEP 4 Set Up Problem mol C 9 H 8 O 4 x 4 mol O x x O atoms 1 mol C 9 H 8 O 4 1 mol O = 3.61 x O atoms

18 Molar Mass 18 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 19

20 Molar Mass from the Periodic Table 20

21 Learning Check Give the molar mass for A. 1 mol of K atoms = B. 1 mol of Sn atoms = 21

22 Solution Give the molar mass for A. 1 mol of K atoms = g B. 1 mol of Sn atoms = g 22

23 Guide to Calculating Molar mass 23

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 CaCl 2. Element Number of Moles Atomic Mass Total Mass Ca g/mol g Cl g/mol g CaCl g 24

25 Molar Mass of K 3 PO 4 Determine the molar mass of K 3 PO 4. Element Number of Moles Atomic Mass Total Mass in K 3 PO 4 K g/mol g P g/mol g O g/mol g K 3 PO g 25

26 Some One-Mol Quantities 26

27 Learning Check Calculate the molar mass for Al(OH) 3 with four significant figures. 1) g/mol 2) g/mol 3) g/mol 27

28 Solution STEP 1 Obtain the molar mass of each element. Al g/mol O g/mol H g/mol STEP 2 Multiply each by the subscript. 1 mol Al x g Al = g 1 mol Al 3 mol O x g O = g 1 mol O 3 mol H x g H = g 1 mol H STEP 3 Calculate the molar mass by adding the masses of the elements. 1 mol of Al(OH) 3 = g (3) 28

29 Learning Check Prozac, C 17 H 18 F 3 NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? 1) g/mol 2) g/mol 3) g/mol 29

30 Solution Prozac, C 17 H 18 F 3 NO, 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 g/mol H g/mol F g/mol N g/mol O g/mol STEP 2 30 Multiply each by the subscript in the formula. 17 mol C x g C = g 1 mol C 18 mol H x g H = g 1 mol H

31 Solution (continued) STEP 2 3 mol F x g F = g 1 mol F 1 mol N x g N = g 1 mol N 1 mol O x g O = g 1 mol O STEP 3 1 mol of C 17 H 18 F 3 NO = g 31

32 Calculations Using Molar Mass Calculations Using Molar Mass Table salt is NaCl. 32

33 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 CH 4 used in gas cook tops and gas heaters. Molar mass: 1 mol CH 4 = g Conversion factors: g CH 4 and 1 mol CH 4 1 mol CH g CH 4 33

34 Learning Check Acetic acid HC 2 H 3 O 2 gives the sour taste to vinegar. Write an equality and two molar mass conversion factors for acetic acid. 34

35 Solution Acetic acid HC 2 H 3 O 2 gives the sour taste to vinegar. Write an equality and two molar mass conversion factors for acetic acid. Equality: 1 mol of acetic acid = g of acetic acid Molar mass conversion factors: 1 mol acetic acid and g acetic acid g acetic acid 1 mol acetic acid 35

36 Guide to Calculation Using Molar Mass 36

37 Moles to Grams Aluminum is used to build lightweight bicycle frames. How many grams of Al are in 3.00 mol of Al? 37

38 Solution 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 = g of Al 1 mol Al and g Al g Al 1 mol Al 38

39 Solution (continued) STEP 4 Set Up Problem Set up with molar mass as a factor: 3.00 mol Al x g Al = 80.9 g of Al 1 mol Al molar mass factor for Al 39

40 Learning Check The artificial sweetener aspartame (NutraSweet), C 14 H 18 N 2 O 5, is used to sweeten diet foods, coffee, and soft drinks. How many moles of aspartame are present in 225 g of aspartame? 40

41 Solution STEP 1 Given 225 g of C 14 H 18 N 2 O 5 Need moles STEP 2 Plan g of aspartame moles of aspartame STEP 3 Equalities/Conversion Factors 1 mol aspartame = g 1 mol aspartame and g aspartame g aspartame 1 mol aspartame STEP 4 Set Up Problem 225 g aspartame x 1 mol aspartame g aspartame mole factor (inverted) = mol of aspartame 41

42 Learning Check Allyl sulfide, C 6 H 10 S, is a compound that has the odor of garlic. How many moles of C 6 H 10 S are in 225 g of C 6 H 10 S? 42

43 Solution STEP 1 Given 225 g of C 6 H 10 S Need moles of C 6 H 10 S STEP 2 Plan g of C 6 H 10 S moles of C 6 H 10 S STEP 3 Equalities/Conversion Factors 1 mol of C 6 H 10 S = g of C 6 H 10 S 1 mol C 6 H 10 S and g C 6 H 10 S g C 6 H 10 S 1 mol C 6 H 10 S STEP 3 Set Up Problem 225 g C 6 H 10 S x 1 mol C 6 H 10 S g C 6 H 10 S = 1.97 mol C 6 H 10 S 43

44 Guide to Converting Grams to Particles 44

45 Learning Check How many molecules of H 2 O are in 24.0 g of H 2 O? 1) 4.52 x ) 1.44 x ) 8.02 x

46 Solution STEP 1 Given 24.0 g of H 2 O Need molecules of H 2 O STEP 2 Plan g of H 2 O moles of H 2 O molecules of H 2 O STEP 3 Equalities/Conversion Factors 1 mol of H 2 O = g of H 2 O 1 mol H 2 O and g H 2 O g H 2 O 1 mol H 2 O 46

47 Solution (continued) STEP 3 Equalities/Conversion Factors (continued) 1 mol of H 2 O = molecules of H 2 O 1 mol H 2 O and x H 2 O molecules H 2 O molecules 1 mol H 2 O STEP 4 Set Up Problem 24.0 g H 2 O x 1 mol H 2 O g H 2 O x x H 2 O molecules 1 mol H 2 O = 8.02 x H 2 O molecules (3) 47

3/17/2017. Avogadro s Number. Collection Terms. A Mole of Atoms. A Mole of A Compound. Samples of One Mole Quantities.

3/17/2017. Avogadro s Number. Collection Terms. A Mole of Atoms. A Mole of A Compound. Samples of One Mole Quantities. Chapter 7 Lecture Chapter 7 Chemical Quantities 7.1 The Mole Fifth Edition Collection Terms A collection term states a specific number of items. 1 dozen donuts = 12 donuts 1 ream of paper = 500 sheets