Chapter 7 Chemical Quantities 7.1 The Mole Learning Goal Use Avogadro's number to determine the number of particles in a mole. © 2014 Pearson Education, Inc.

Calculating a Percentage (1.4C) Solving Equations (1.4D) Chapter 7 Readiness Key Math Skills Calculating a Percentage (1.4C) Solving Equations (1.4D) Using Scientific Notation (2.2) © 2014 Pearson Education, Inc.

Counting Significant Figures (2.3) Chapter 7 Readiness Core Chemistry Skills Counting Significant Figures (2.3) Using Significant Figures in Calculations (2.4) Writing Conversion Factors from Equalities (2.6) Using Conversion Factors (2.7) © 2014 Pearson Education, Inc.

The Mole Counting Units 1 dozen = 12 1 case = 24 cans Avogadro’s number = 6.022 × 1023 Atoms are so small it takes a large number of them to weigh and use in a chemical reaction. © 2014 Pearson Education, Inc.

One mole of any element contains 6.022 × 1023 atoms of that element. Avogadro’s Number A mole (mol) is a unit that represents the same number of particles as there are carbon atoms in 12.01 g of carbon. One mole of any element contains 6.022 × 1023 atoms of that element. 1 mol of Element Number of Atoms 1 mol C = 6.022 × 1023 C atoms 1 mol Au = 6.022 × 1023 Au atoms © 2014 Pearson Education, Inc.

an element contains 6.022 × 1023 atoms Avogadro’s Number One mole of an element contains 6.022 × 1023 atoms a molecule contains 6.022 × 1023 molecules an ion contains 6.022 × 1023 ions a formula unit contains 6.022 × 1023 formula units © 2014 Pearson Education, Inc.

Number of Particles in One Mole © 2014 Pearson Education, Inc.

Avogadro’s number as a Conversion Factor Avogadro’s number (6.022 × 1023) can be written as an equality and two conversion factors. Equality: 1 mole = 6.022 × 1023 particles Conversion Factors: © 2014 Pearson Education, Inc.

Using Avogadro’s Number Avogadro’s number converts moles of a substance to the number of atoms. How many Cu atoms are in 0.50 mol of Cu? © 2014 Pearson Education, Inc.

Using Avogadro’s Number Avogadro’s number converts the number of molecules to moles of a molecule. How many moles of CO2 are in 2.50 × 1024 molecules of CO2? 2.50 × 1024 molecules CO2 = 4.15 mole CO2 © 2014 Pearson Education, Inc.

Guide to Calculating the Atoms or Molecules of a Substance © 2014 Pearson Education, Inc.

The number of atoms in 2.0 moles of aluminum is A. 2.0 Al atoms Learning Check The number of atoms in 2.0 moles of aluminum is A. 2.0 Al atoms B. 3.0 × 1023 Al atoms C. 1.2 × 1024 Al atoms © 2014 Pearson Education, Inc.

Solution The number of atoms in 2.0 moles of aluminum is Step 1 State the given and needed quantities. Given = 2.0 moles Al Need = atoms of Al Step 2 Write a plan to convert moles to atoms. Moles Al atoms Al Avogadro’s Number © 2014 Pearson Education, Inc.

The number of atoms in 2.0 moles of aluminum is Solution The number of atoms in 2.0 moles of aluminum is Step 3 Use Avogadro’s number to write conversion factors. Equality: 1 mole Al = 6.022 × 1023 atoms Al © 2014 Pearson Education, Inc.

The number of atoms in 2.0 moles of aluminum is Solution The number of atoms in 2.0 moles of aluminum is Step 4 Set up the problem to calculate the number of particles = 1.2 × 1024 atoms Al Answer C is correct. © 2014 Pearson Education, Inc.

Moles of Element in a Chemical Formula The subscripts in a formula state the relationship of atoms in the formula the moles of each element in one mole of compound NH3 1 molecule 1 atom N 3 atoms H 1 mole NH3 1 mole N 3 moles H © 2014 Pearson Education, Inc.

Chemical Formulas, Subscripts Aspirin, C9H8O4, is used to reduce pain and inflammation. © 2014 Pearson Education, Inc.

Chemical Formulas, Subscripts The subscripts in the chemical formula for aspirin, C9H8O4, express the ratio of atoms or moles. © 2014 Pearson Education, Inc.

Chemical Formulas, Conversion Factors The subscripts from the formula, C9H8O4, can be used in conversion factors. © 2014 Pearson Education, Inc.

Guide to Calculating Moles © 2014 Pearson Education, Inc.

How many moles of carbon are present in 2.50 moles of aspirin, C9H8O4? Learning Check How many moles of carbon are present in 2.50 moles of aspirin, C9H8O4? © 2014 Pearson Education, Inc.

Solution How many moles of oxygen are present in 2.50 moles of aspirin, C9H8O4? Step 1 State the given and needed quantities. Given: 2.50 moles aspirin, C9H8O4 Need: moles of O Step 2 Write a plan to connect moles of a compound to moles of an element. moles C9H8O4 moles O Subscript © 2014 Pearson Education, Inc.

Solution How many moles of oxygen are present in 2.50 moles of aspirin, C9H8O4? Step 3 Write equalities and conversion factors. 1 mole C9H8O4 = 4 moles O © 2014 Pearson Education, Inc.

How many moles of oxygen are present in 2.50 moles of aspirin, C9H8O4? Solution How many moles of oxygen are present in 2.50 moles of aspirin, C9H8O4? Step 4 Set up the problem to calculate the moles of an element.   © 2014 Pearson Education, Inc.

Learning Check The number of moles of sulfur (S) in 1.8 × 1024 atoms of sulfur is _____. A. 1.0 mol of S atoms B. 3.0 mol of S atoms C. 1.1 × 1048 mol of S atoms © 2014 Pearson Education, Inc.

The number of moles of sulfur (S) in 1.8 × 1024 Solution The number of moles of sulfur (S) in 1.8 × 1024 atoms of sulfur is _____. Step 1 State the given and needed quantities. Given: 1.8 × 1024 atoms of S Need: moles of S Step 2 Write a plan to connect moles to atoms or molecules. atoms S moles S Avogadro's number © 2014 Pearson Education, Inc.

Step 3 Use Avogadro’s number to write conversion factors. Solution The number of moles of sulfur (S) in 1.8 × 1024 atoms of sulfur is _____. Step 3 Use Avogadro’s number to write conversion factors. 1 mole S = 6.022 × 1023 atoms © 2014 Pearson Education, Inc.

Step 4 Set up the problem to calculate the number of particles. Solution The number of moles of sulfur (S) in 1.8 × 1024 atoms of sulfur is _____. Step 4 Set up the problem to calculate the number of particles. The correct answer is B. © 2014 Pearson Education, Inc.