Chemical Quantities Chapter 10:The Mole Measuring Matter: If one marble has a mass of 4.5g, how many kilograms will 230 marbles have? ans: 1.035 Kg How many grass seeds are in a 40 kg bag of seeds if one grass seed has a mass of 0.125g? ans: 320 000 seeds

The Mole: An expression of the quantity of matter. The quantity of matter is referred to a representative particles. One mole = 6.023 x 1023 quantity (Avogadro’s #) The representative particles are: 1. Atoms: One mole of atoms = 6.023 x 1023 atoms. 2. Molecules: One mole of molecules = 6.023 x 1023 molecules. 3. Ions: One mole of ions = 6.02 x 1023 ions 4. Compounds: One mole of compound = 6.023 x 1023 compounds. The Mole Concept

To find Molar Mass: Gram atomic mass (gam) is the mass of the atom Reference off the periodic table. Cl Ni Ba Ag N

To find Molar Mass: Gram molecular mass (gmm) is the sum of mass of atoms in a molecule. CO2 C2H8 NO2 Cl2 CCl4 N2

To find Molar Mass: Gram formula mass (gfm) is the sum of the mass of atoms in an ioinc compound. NaCl Na2SO4 Fe2O3 Ba3(PO4)2

Determine the Molar Mass Find the gam for Ca ______ and Pb ______ Find the gfm for K2CrO4 Find the gmm for N2O5 TLS: Complete Molar Mass Review HW: #34-36 all page 335

The Mole Concept Sampler Text page 323, Practice #1-4. Text page 324, Practice #5-6 Text page 335, Problems #34-36

To determine: The mass in moles of an atom: reference the periodic table. Note: 1 mole of Na atoms = 6.02 x 1023 Na atoms = 23g (the atomic mass of Na) *the atomic mass of any element is the molar mass (in g/mol) of that element. The Mole Concept flowchart.

The Mole Concept

The mass to mole relationship. Find the gfm, gmm, or gam for the given compound Convert given # if grams to moles of compound using 1 mole = gfm, gmm or gam How many moles in 2.5 g of NaCl? 2. How many moles of N2O5 are in 35 g of N2O5?

*the mole to mass relationship. 3. How many grams of CO2 gas are in 2.5 moles of CO2 gas? 4. How many grams of chlorine gas are in 40 moles of chlorine gas?

*The Mole to Mass and Mass to Mole Relationship for Elements : Text page 328-329, Practice #15-#18 #15b #17b

The # of molecules in a given # of moles. Write the # of moles given Use the molecules to mole relationship. 1 mole of molecule = 6.02 x 1023 molecules. How many molecules are in 2 moles of H2O? How many moles of hydrogen are in 2 moles of H2O? TLS: Practice #29-#36 pp335.

Apply the Mole Concept Given mass converts to mole using (1 mole = gfm, gmm,or gam)  Mole converts to molecule using (1 mole = 6.023 x 1023 ) Number of Molecules. How many molecules of CO2 are there in 23 g of CO2? Ans: 3.15 x 1023 molecules of CO2 HW: Problem Set Three Textbook: page 331 #19-20 and page 339 #42-46

Percent Composition refers to what part by mass of a compound does each element contribute. NOTE page 342. Formula: MolarMass of element X 100 = % Molar Mass of compound

Sample Calcium Chloride : CaCl2 Ca: 1 x 40 = 40 Cl: 2 x 35 = 70 110 is the total mass % Comp Ca = 40 x 100 = 36.36 % 110 % Comp Cl = 70 x 100 = 63.6 % 110 100 % TLS: Practice #54-57 pp 344.

Empirical Formula Expression of the smallest whole number ratio of elements in a molecule. 1. May or may not be the same as the molecular formula. 2. Total percentage of any compound is 100%. The % = mass a. Given 36.63% Ca will = 36.63 g Ca

Procedures: Empirical Formula 1. Convert % to mass (total percentage is 100%). 2. Convert mass to moles via the gfm. 3. Divide the moles by the smallest mole value to determine the mole ratio within the compound. 4. If not a whole number, multiply the mole ratio from #3 by the smallest whole #. 5. The answers are the subscript in the empirical formula.

Sampler #1 The % composition of an unknown compound is found to be 38.43% Mn, 16.80% C and 44.77% O. What is the empirical formula for this compound?

Sampler #2 Calculate the empirical formula for a compound whose % composition is 74.97% Al and 25.03% C ?

Sampler #3 What is the empirical formula of compound composed of 37.01 % Carbon, 2.22 % Hydrogen, 18.50 % Nitrogen, and 42.27% Oxygen? HW: #58-61 page 346

Molecular Formula Actual number of elements expressed in a molecule. a. molecular formula = empirical formula x n b. Formula: molar mass of the molecule = MW = n mass of the empirical formula EW n = the number of moles

Sampler Molecular Formula A compound has a molecular mass of 118 g/mol and is composed of 40.68% carbon, 5.08% H and 54.24% O. What is the molecular formula? Page 350, #65 TLS: Practice #62-64 pp 350.

Hydrates Compounds with water molecules attached. a. Review the prefixes. (Table 10-1, pp 351) b. The mass of the water is included in the mass of the total molecule. c. Calculation of % composition, empirical formula and molecular formula is the same with hydrate. EXCEPT the mass of the water molecules are included. TLS: Practice #74 and #75 p 353

Hydrated Sample A hydrate of aluminum bromide is composed of 71.16% AlBr3 and 28.84% H2O. What is the formula for this hydrate?

Hydrated Sampler #2 A 17.44 g sample of hydrated zinc (II) sulfate is heated to drive off the water. After heating, 9.79 g of anhydrous zinc(II) sulfate remain. Find the hydrated formula.

Hydrated Sampler #3 What is the % composition of a hydrated Lead (II) acetate if the molecule is composed of 14.25% water by mass? What is the hydrated formula? Page 361; #184 and #185