CHEM 031 Lecture Notes - Lecture 3: Radioactive Decay, Bromine, Molar Mass
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Avogadro"s number - represents 1 mole, 6. 022 x 10^23 entities (often atoms: you can find out how much (g) of something you want by the amount of moles needed, ex. 1 molecule of h2o has 18. 02amu, 1 mole of h2o is 80. 2amu and a mass of 18. 02g, molar mass of h2o is 80. 2amu: ex. Sodium is 22. 99g so 22. 99g/mol aka 1 mole has 22. 99g of sodium: amu = g/mol, ex. Br2 = 2(79. 9g/mol)=159. 809g/mol: mass moles, ex. How many moles of h2o in 10g? (molar mass of h2o = 18. 2g/mol: 10. 00g(mol/18. 2g) = 0. 5549mol, moles of compounds moles of elements, ex. How many moles of h atoms are in 0. 500 moles of ch4: 4molh/1molch4(0. 5molch4) = 2. 00mol h, number of entities moles, ex. How many molecules are in 2. 50 moles of ch4: 2. 5mol(6. 022x10^23entities/1mol) = 1. 5 x 10^24 entities. Figuring out mass percent of a compound: ex.