12 Mass Mole conversions Example:Calculate the mass in grams of mol Cr.Work Practice problems 1-4
13 Hydrate: CuSO4·5H2O4) Calculate the mass in grams of 2.45 mol of CaCl2·2H2O
14 Mole Mass conversions Example:Determine the number of moles for 25.5 g Ag. (mass mol)Work practice problems 5-7.**worksheet: moles & mass
15 Mass Atom Conversion Example: How many atoms of gold (Au) are in a pure nugget having the mass of 25.0g?Practice problems 1-5
16 Atom Mass Conversion Example A party balloon contains 5.50 x 1022 atoms of helium (He) gas. What is the mass in grams of the helium?Practice problems 6-10.
17 Mole MoleExampleAccording to the following balanced equation, how many moles of O2 is produced from 3.00 moles of CuO?2CuO 2Cu + O2Practice problems 1 & 2.
18 Section 11.4 Empirical & Molecular Formula Percent Composition is the percent by mass of each element in a compound.Example:If we had 100 g of a sample of some new compound contains 55g of element X & 45 g of element Y. What is the % of element X & Y?
19 Mass of element in 1 mol of compound X 100 If we already know the _chemical formula for a compound, you can calculate its percent composition.% by mass=Mass of element in 1 mol of compound X 100Molar mass of compound
20 Ex. Determine the percent composition of H2O. (If you had 350. g of water, then how much is oxygen?)Practice problems 1-3.311g
21 Empirical Formula is the smallest whole number ratio of the elements. Calculating Empirical formula from percent composition:Directions:The percent should be assumed to be 100 g & converted to moles. Then we figure out the mole ratio by dividing each by the smallest mole.
22 POEM:Percent to MassMass to MoleDivide by smallMultiply til whole.
23 Example 1The percent composition of an oxide of sulfur is 40.05% S & 59.95% O.Example 2Determine the empirical formula for methyl acetate which has the following chemical analysis:48.64% C, 8.16% H, & 43.20% O.Practice Problems