1. Moles and Mass LG: I can use molar mass to convert between mass and moles

2. Relative Atomic Mass The mass of all elements on the periodic table relative to carbon-12. – ie. An atom of hydrogen is assigned a mass of ~ 1µ, because it is roughly 1/12 the mass of an atom of carbon-12 The ratio of masses hold true as long as the units are the same – Example: A mole of hydrogen weighs 1g, a mole or carbon weighs 12g

3. Molar Mass The mass of one mole of a substance is the “molar mass” – Molar Mass Units: g/mol Symbol: M – Recall: Chemists decided to take the atomic weight of an element and define the number of particles in that many grams to be one mole. – Example: What is the molar mass of: Argon, ArOxygen, O 2 Sulfur, S 8 Magnesium chloride, MgCl 2

4. Calculations with Molar Mass Molar mass can be used to convert between mass and moles – Mass Units: gSymbol: m Think about the units involved to answer the following: – What is the molar mass of lithium? – What is the mass of 4.5 moles of lithium? – How many moles of lithium are contained in a 28g sample?

5. Practice What is the mass of 4.2 moles of sodium hydroxide? A can of coke contains 40.0g of sucrose, C 12 H 22 O 11 how many moles of sucrose are in a can of coke?

6. “The Mole Bridge” By combining two formulas, moles can be used to convert between mass and number of entities Example: how many atoms are in a 7.2g sample of carbon?

7. Homework New Text: Pg 277 # 1, 3-12 Old Text: Pg 172-177 # 1- 3, 5, 8-13 (“practice”, not “section” questions) Mark your Calendar!