Name Block THE MOLE. Who s Counting Lab. Mole Notes. Mole Calculations. Mixed Mole Conversions. % Comp, Emp, and Molecular Calcuations

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1 Name Block THE MOLE Who s Counting Lab Mole Notes Mole Calculations Mixed Mole Conversions % Comp, Emp, and Molecular Calcuations

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3 Mole Notes, Part 1 1. The Mole is just a long word for changing units in chemistry The (mol) is the SI base unit used to measure the of a substance. A mole of anything contains representative particles. a. A representative particle = any kind of particle (atoms, molecules, formula units, electrons, or ions). b x is called number Conversion Factor: Anything Elements Covalent Compounds Ionic Compounds Ions - Calculate the number of molecules in 2.6 moles of H 2 O Calculate the number of formula units in 5.23 moles of NaCl 2. Molar Mass The mass in grams of 1 mole of a substance is called the To get the molecular weight you just add up all of the masses of all of the elements in a compound Conversion Factor: How many moles of F are in 5.50 mol of CCl 2 F 2? How many moles of Al are in 1.25 mol of Al 2 O 3? How many Cl - ions are in 35.6 g of AlCl 3? How many Al +3 ions?

4 Mole Notes, Part 2 3. Percent Composition % = (part / whole ) x 100 Calculate the % Composition of MgO Calculate the % Composition of iron (III) oxide 4. Empirical and Molecular Formula the smallest whole number ratio of elements the true number of elements in a compound What is the empirical formula for C 6 H 12 O 6? Steps to write empirical formulas: 1. List your givens 2. Change % to grams 3. Change grams to moles 4. Divide everything by the smallest number of moles 5. Write your formula Calculate the empirical formula of a compound containing % S and % O. Calculate the empirical formula for a compound containing g C, 8.16 g H, and g O.

5 Mole Notes, Part 3 Steps to write molecular formulas: 1. Calculate the empirical formula 2. Get the molecular mass of the empirical formula that you just determined 3. Divide the experimentally determined molecular mass (given) by the molecular mass of the empirical formula 4. You will get a whole number 5. Multiply everything in the empirical formula by this number Calculate the molecular formula of a compound containing 40.68%C, 5.08%H, and 54.25%O with an experimentally determined molecular weight of g/mol Calculate the molecular formula of a compound containing g C, 3.64 g H, and g O with an experimentally determined molecular mass of g/mol Calculate the molecular formula of a compound with an empirical formula of C 2 OH 4 and a molar mass of 88 grams per mole. Calculate the molecular formula of a compound with an empirical formula of C 4 H 4 O and a molar mass of 136 grams per mole.

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8 Mixed Mole Conversions Given unit Moles Desired unit 1. Find the mass in grams of 2.00 x 1023 molecules of F g 2. Find the mass, in grams, of 1.00 x 1023 molecules of N2. 3. How many particles are there in 1.43 g of a molecular compound with a gram molecular mass of 233 g? 4. Aspartame is an artificial sweetener that is 160 times sweeter than sucrose (table sugar) when dissolved in water. It is marketed by G.D. Searle as Nutra Sweet. The molecular formula of aspartame is C14H18N2O5. a) Calculate the gram-formula-mass of aspartame. b) How many moles of molecules are in 10 g of aspartame? c) What is the mass in grams of 1.56 moles of aspartame? d) How many molecules are in 5 mg of aspartame? e) How many atoms of nitrogen are in 1.2 grams of aspartame? 5. Convert 10.0g of potassium phosphate (K 3 PO 4 ) to molecules g of silicon dioxide to molecules of silicon dioxide g of aluminum hydroxide to molecules of aluminum hydroxide x10 23 atoms of sulfur to grams of sulfur x10 24 atoms of ammonium chloride to grams of ammonium chloride.

9 Chemistry: Percentage Composition and Empirical & Molecular Formula Solve the following problems. Show your work, and always include units where needed. 1. A compound is found to contain 36.5% Na, 25.4% S, and 38.1% O. Find its empirical formula. 2. Find the empirical formula of a compound that is 53.7% iron and 46.3% sulfur. 3. Analysis of a sample of a compound indicates that is has 1.04 g K, 0.70 g Cr, and 0.86 g O. What is its empirical formula? 4. If 4.04 g of nitrogen combine with g of oxygen to produce a compound with a molar mass of 108.0g, what is the molecular formula of this compound? 5. The molar mass of a compound is 92 g. Analysis of the sample indicates that it contains g N and g O. Find the compound s molecular formula.

10 6. An acid commonly used in the automotive industry is shown to be 31.6% phosphorous, 3.1% hydrogen, and 63.5% oxygen. Determine the empirical formula of this acid. 7. A solvent is found to be 50.0% oxygen, 37.5% carbon, and 12.5% hydrogen. What is the empirical formula of this solvent. 8. A particular sugar is determined to have the following composition: 40.0% carbon, 6.7% hydrogen, and 53.5% oxygen. Determine the empirical formula of this sugar molecule. 9. If the molar mass of the sugar in question #8 is g, find the molecular formula of the sugar. 10. Ethene, a gas used extensively in preparing plastics and other polymers, has a composition of 85.7% carbon and 14.3% hydrogen. Its molar mass is 28 g. Find the molecular formula for ethane.

Calculating Atoms, Ions, or Molecules Using Moles

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