Modern Chemistry Chapter 7 Chemical Formulas and Chemical Compounds Sections 1, 3 & 4 Chemical Names and Formulas Using Chemical Formulas Determining Chemical Formulas Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Monatomic ion Binary compound Nomenclature Oxyanion Salt Formula Mass Percent Composition Empirical Formula Chapter Vocabulary Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Using Chemical Formulas Section 3 Using Chemical Formulas Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Atomic Mass Animation Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Definitions Formula Mass – the mass of any molecule, formula unit or ion. The sum of all the average atomic masses of all the atoms represented by the formula Unit: a.m.u. Molecular mass Mass of a molecule – in a.m.u. Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Definitions Molar mass – the mass of one mole of atoms of an element The mass of one mole of molecules or formula units of a compound Numerically equal to formula mass Unit: grams/mole (g/mol) Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Calculating Formula Mass or Molar Mass List the elements in the compound. List the number of atoms of each element. Multiply each number of atoms by the Relative atomic mass (for formula mass) Molar mass (for molar mass) Add the products. Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Calculating Formula Mass or Molar Mass (NH4)2SO4 N H S O 2 8 1 4 x 14.01 = 28.02 x 1.008 = 8.064 x 32.06 = 32.06 x 16.00 = 64.00 + Multiply each number of atoms by the Relative atomic mass (for formula mass) Molar mass (for molar mass) 132.144 Add the products… List the elements in the compound. List the number of atoms of each element. Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Calculating Formula Mass or Molar Mass (NH4)2SO4 N H S O 2 8 1 4 x 14.01 = 28.02 x 1.008 = 8.064 x 32.06 = 32.06 x 16.00 = 64.00 132.144 The unit is amu for formula mass. The unit is g/mol for molar mass From the periodic table 4 sig figs Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 1. Find the formula mass of each of the following: a. H2SO4 b. Ca(NO3)2 c. PO4 3− d. MgCl2 Practice Page 238 Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 2. Find the formula mass of each of the following: a. Al2S3 b. NaNO3 c. Ba(OH)2 Practice Page 239 Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 One mole of … Nitrogen (balloon) CdS (yellow) Water (cylinder) NaCl (white) Ch 7 Sec 3 Using Chemical Formulas pages 237-244 p. 239

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Mole Animation Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Chemical Formulas & Moles 2 The formula could stand for 1 molecule of water with 2 hydrogen atoms and 1 oxygen atom… or … The formula could stand for 1 mole of water molecule which contain 2 moles of hydrogen atoms and 1 mole of oxygen atoms. Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Conversions with Compounds   AMOUNT moles MOLAR MASS 6.022 x 10 23 x x MASS grams PARTICLESmolecules Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Conversions with Compounds   AMOUNT moles MOLAR MASS 6.022 x 10 23 x x MASS grams PARTICLESatoms Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Grams-Moles-Molecules Conversions Ch 7 Sec 3 Using Chemical Formulas pages 237-244 p. 240

gmol Conversion Animation Ch 7 Sec 3 Using Chemical Formulas pages 237-244 p. 240

Dimensional Analysis # & unit given unit given unit wanted x = Put in numbers to make the numerator equal to the denominator x = unit given Fill in units first; then numbers ! Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Dimensional Analysis x x x x = Arrange the units so that all cancel out except the last one, which should be the one you want. Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 1. How many moles of atoms of each element are there in one mole of the following compounds? a. Al2S3 b. NaNO3 c. Ba(OH)2 2. Find the molar mass of each of the compounds listed in item 1. Practice Page 239 Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 1. How many moles of compound are there in the following? a. 6.60 g (NH4)2SO4 b. 4.5 kg Ca(OH)2 2. How many molecules are there in the following? a. 25.0 g H2SO4 b. 125 g of sugar, C12H22O11 3. What is the mass in grams of 6.25 mol of copper(II) nitrate? Practice Page 242 Ch 7 Sec 3 Using Chemical Formulas pages 237-244

% Composition Animation Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Percent Composition (NH4)2SO4 N H S O 2 8 1 4 x 14.01 = 28.02 x 1.008 = 8.064 x 32.06 = 32.06 x 16.00 = 64.00  132.14 = .2120  132.14 = .06103  132.14 = .2426  132.14 = .4843 132.144 Find the molar mass of the compound. Divide the subtotal for each element by the molar mass Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Percent Composition (NH4)2SO4 N H S O 28.02 8.064 32.06 64.00  132.14 = .2120  132.14 = .06103  132.14 = .2426  132.14 = .4843 x100 = 21.20% x100 = 6.103% x100 = 24.26% x100 = 48.43% 132.144 Multiply each by 100 to get a percent. Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Hydrates Salt which have the ability to bind water molecules within their crystal lattice. Anhydrous - salts without water Examples CuSO4 5H2O copper(II) sulfate pentahydrate CoCl2 6H2O cobalt (II) chloride hexahydrate Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Hydrates CuSO4  5H2O CoCl2  6H2O Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 What percentage of sodium carbonate decahydrate, Na2CO3 10H2O, is sodium carbonate? 1. Find the molar mass of Na2CO3 (the anhydrous compound). 2. Find the mass Na2CO3 10H2O (the hydrate). 3. Divide mass of compound (anhydrous) by mass of the hydrate and multiply by 100. Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Percent Composition of a Hydrate CuSO4  5H2O Cu S O H 1 4 10 5 x 63.55 = 63.55 x 32.06 = 32.06 x 16.00 = 64.00 x 1.008 = 10.08 x 16.00 = 80.00 159.61 x 100 = 63.92% 249.69 90.08 x 100 = 36.08% 249.69 249.69 Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 What is the percentage of MnCl2 in MnCl2 2H2O? 77.73% How much water could 100g of anhydrous MnCl2 absorb if the hydrated form is MnCl2 2H2O? 28.64g Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 1. Find the percentage compositions of the following: a. PbCl2 b. Ba(NO3)2 2. Find the mass percentage of water in ZnSO4•7H2O. 3. Magnesium hydroxide is 54.87% oxygen by mass. How many grams of oxygen are in 175 g of the compound? How many moles of oxygen is this? Practice Page 244 Ch 7 Sec 3 Using Chemical Formulas pages 237-244

Ch 7 Sec 3 Using Chemical Formulas pages 237-244 Section 3 Homework Ch 7 Sec 3 Using Chemical Formulas pages 237-244