The Mole and Stoichiometry Part 2 Molar Mass

The Mole and Stoichiometry Part 2

Molar Mass Review • Mass of one mole of a substance. • Equal to the formula mass of a molecular or ionic compound and the atomic mass of an element. • Measured in grams per mole (g/mol) • Example: Ca. Cl 2 • Formula mass: 111. 1 amu • Molar mass: 111. 1 g/mol • One mole of Ca. Cl 2 contains: • 6. 02 x 1023 formula units • 6. 02 x 1023 atoms of Ca in 1 mole • 1. 20 x 1024 atoms chlorine

Moles Mass • To convert between moles and mass, use the equality 1 mole= molar mass of a substance • This is your conversion factor between moles and mass

Moles Mass Examples • Example 1: What is the mass of 6. 0 moles of potassium chloride? • First calculate the molar mass of KCl • Molar mass KCl= 74. 55 g/mol 6. 0 moles of KCl 74. 55 g of KCl = 447. 3 g of KCl 1 mole of Na. Cl • Example 2: How many moles are 14. 0 grams of water? • First calculate the molar mass of water • Molar mass of H 2 O = 18. 02 g/mol 14. 0 g of H 2 O 1 mole of H 2 O 18. 02 g H 2 O = 0. 78 g H 2 O

Moles Mass Practice 1. How many moles are in 100. 0 grams of carbon dioxide? 2. What is the mass of 3. 2 moles of lithium? 3. What is the mass of 2. 0 x 1017 molecules of water? (hint convert to moles first then convert to mass) 4. How many compounds are in 22. 0 g of copper (II) sulfide?

Moles Mass Practice Answers 1) 2. 27 moles of CO 2 2) 22. 21 g of Li 3) 5. 99 x 10 -6 g of H 2 O Solution: 2. 0 x 1017 molecules H 2 O 1 mole H 2 O 18. 02 g H 2 O 6. 02 x 1023 molecules H 2 O 1 mole H 2 O 4) 8. 32 x 1022 compounds of Cu. S Solution: 22. 0 g Cu. S 1 mole Cu. S 95. 62 g Cu. S 6. 02 x 1023 molecules Cu. S 1 mole Cu. S

Moles Volume • To convert between moles and volume, use the equality 1 mole= 22. 4 L of gas @ STP • This conversion is for Gases ONLY • STP stands for Standard Temperature and Pressure • Standard temperature is 273 K • Standard pressure is 1 atm

Moles Volume Examples • Example 1: What is the volume of 3. 3 moles of chlorine gas? 3. 3 moles of Cl 2 22. 4 L of Cl 2 = 73. 92 L of Cl 2 1 mole of Cl 2 • Example 2: How many moles are in 95. 5 L of water vapor? 95. 5 L of H 2 O 1 mole of H 2 O 22. 4 L H 2 O = 4. 26 moles H 2 O

Moles Volume Practice 1. How many moles are in 56. 7 L of carbon dioxide? 2. What is the volume of 0. 50 moles of oxygen gas? 3. What is the volume of 2. 0 x 1026 molecules of water vapor? (hint convert to moles first then convert to liters) 4. How many diatomic molecules are in 22. 4 L of sulfur dioxide?

Moles Volume Practice Answers 1) 2. 53 moles of CO 2 2) 11. 2 L of O 2 3) 7441. 9 L of H 2 O Solution: 2. 0 x 1026 molecules H 2 O 4) 6. 02 x 1023 molecules SO 2 Solution: 22. 4 L SO 2 1 mole H 2 O 22. 4 L H 2 O 6. 02 x 1023 molecules H 2 O 1 mole SO 2 6. 02 x 1023 molecules SO 2 22. 4 L SO 2 1 mole SO 2

Mixed Mole Practice 1. 2. 3. 4. What is the mass of 5 moles of titanium? What is the volume of 4. 5 x 1042 molecules of Si. O? How many molecules are in 60. 0 L of nitrogen gas? How many molecules are in 45 g of Na. Cl?

Mixed Mole Practice 1) 2) 3) 4) 239. 4 g Ti 1. 67 x 1020 L of Si. O 1. 61 x 1020 molecules of N 2 4. 64 x 1023 molecule Na. Cl