Mole

Objectives:Define mole.Convert mole to number of

particles.

Moleunit used to express amount of

substancebased on a certain number of

particles

Dozen and Mole1 dozen = 12 pieces

1/2 dozen of apples = 6 apples

2 dozens of eggs= 24 eggs

1 mole = 6.02 x 1023 particles

½ mole of C atoms = 3.01 x 1023 C atoms

2 moles of H2O molecules

= 1.20 x 1024 H2O molecules

Moleamount of substance containing

the same number of particles as 12 g of C-12.

1 mole contains 6.02 x 1023 particles (Avogadro’s number)

Particles – may be atoms, molecules, ions

Check for Understanding1. How many atoms are there in 1.0

mole sample of Fe? 2. How many molecules are there in

2.5 moles of CO2?

Mole and Number of Particles1 mole of any substance contains

6.02 x 1023 particles (atoms, molecules, ions)

1 mole C-12

6.02 x 1023 atoms

1 mole CO2

6.02 x 1023 molecules

Mole – Number of Particles Conversion

Mole Number of Particles

x 6.02 x 1023 particles/mole

Sample Problem 1: How many molecules are there in 0.25 moles of H2O?

0.25 mol H2O x 6.02 x 1023 molecules H2O mol

= 1.505 x 1023 molecules H2O

Mole – Number of Particles Conversion

Mole Number of Particles

Sample Problem 2: How many moles are there in 1.2 x 1024 molecules of H2O?

1.2 x 1024 molecules H2O x 1 mole H2O 6.02 x 1023 molecules H2O

= 2.0 moles H2O

/ 6.02 x 1023 particles/mole

Do the following conversions:1) 1.8 x 1024 molecules NH3 = _____ moles

2) 0.75 moles Cl2 = _____ molecules3) 3.0 moles Fe = _____ atoms4) 3.01 x 1023 ions of NO3

- = _____ moles

Closure: Think-Pair-Share

How many molecules are there in 3.0 moles of CO2?

1. Think about how you will go about answering this question.

2. With your group mates, figure out the answer to the question.

3. Make sure everyone in the group knows how to find the answer.

4. If your group is chosen and is able to show the class how to find the correct answer, you earn 3 extra credit points.

 

 

Check for Understanding1. How many atoms are there in 1.0

mole sample of Fe? 2. How many molecules are there in

2.5 moles of CO2?

3. What is 1.806 x 1024 atoms of Cu in number of moles?

Molar Mass

 

1 mole C-12

6.02 x 1023 atoms

12 g

1 mole CO2

6.02 x 1023 molecules

44 g

Molar Mass

Molar mass – mass of 1 mole of a substance (in grams) - equals the total mass of all the atoms in a

substance

What is the molar mass of H2O?H O

2 moles 1 mole2 (1g) = 2g 1(16g) = 16g

2g+ 16 g = 18 gThe molar mass of H2O is 18g.

Molar Mass

What is the molar mass of Mg(OH)2?Mg H O1 mole 2 moles 2 moles

1(24g) = 24 g 2 (1g) = 2g 2 (16g) = 32g

24g+ 2 g +32 g = 58 g

The molar mass of Mg(OH)2 is 58g.

Check for Understanding

What is the molar mass of:

1. NH3

2. Cl23. Cu4. KNO3

5. Mg3(PO4)2

Closure: Write-Pair-Share

1.In your own words, describe how the molar mass of a substance is calculated.

2. Share your answer with your group mates.

3. Make sure that everyone in the group has the correct answer to the question.

4. If your group is chosen and is able to give the correct answer, you earn 2 extra credit point.

 

 

Objective:Do mass-mole conversions.

Mole –Mass Conversion

Mass Mole

/ Molar Mass

x Molar Mass

Sample Problem 1: What is the mass of 0.25 moles of H2O?

Mass of H2O = 0.25 mol x 18 g mol

= 4.5 g

Mole –Mass Conversion

Mass Mole

/ Molar Mass

x Molar Mass

Sample Problem 2. How many moles are there in 36 g of H2O?

Moles of H2O = 36 g x 1 mol 18g

= 2.0 mol

Do the following conversions:1) 25 g NH3 = _____ moles2) 0.75 g Cl2 = _____ moles3) 3.0 moles Fe = _____ grams4) 4.5 moles KNO3 = _____ grams

Check for Understanding

Closure: Write-Pair-Share

1.In your own words, describe how you can do mass to mole and mole to mass conversions.

2. Share your answer with your group mates.

3. Make sure that everyone in the group has the correct answer to the question.

4. If your group is chosen and is able to give the correct answer, you earn 3 extra credit points.

 

 

Vocabulary Review

1. Solution2. Solute3. Solvent4. Dilute5. Concentrated

 

 

Objectives

1. Define molarity.2. Solve molarity problems.3. Prepare a solution of a given molar concentration.

 

 

Molarity- unit of solution concentration

- equal to number of moles of solute per liter (or dm3) of solution 

 

 

Molarity Mole of solute Liter of solution

=

Molarity1. What is the molarity of a 2 L solution that contains 1 mole of solute?

 

 

Molarity Mole of solute Liter of solution

=

= 1 mol

2 L

= 0.5 mol/L

= 0.5 M

Molarity2.) 29g of NaCl is dissolved in enough water to make a 1L solution. What is the molarity of this solution?

 

 

Molarity Mole of solute Liter of solution

=

=

29 g

1 L

= 0.50 mol/L

= 0.50 M

X 1 mol

58 g

Check for Understanding

Solve these problems: 1. What is the molarity of a 3.00 L solution that contains 4.00 moles of solute?

2. If 18.5 g of KCl is dissolved in enough water to produce 0.5 L of solution, what is the molarity of the solution?

3. If 5.00 g of KBr is dissolved in enough water to produce 500.0 mL of solution, what is the molarity of the solution?

Molarity3.) How many grams of NaCl is needed to produce 1.0 L of a 0.75 M solution?

 

 

Molarity Mole of solute Liter of solution

=

= Mole of solute

1.0 L

= 0.75 mol x 58 g/mol

= 43.5 g = 44 g

0.75 M

Mole of solute = 0.75 mol/L x 1.0L = 0.75 mol

Mass of solute

Check for Understanding

Solve this problem: 1. How many grams of KCl should be dissolved in water to produce 0.50 L of a 1.0 M solution?

Closure: Write-Pair-Share

1.Answer this question alone:How many grams of KI are needed to produce 1 L of

0.25 M KI solution.

2. Share your answer with your group mates.

3. Make sure that everyone in the group has the correct answer to the question.

4. If your group is chosen and is able to give the correct answer, you earn 3 extra credit points.