Presentation on theme: "CHEM 5013 Applied Chemical Principles"— Presentation transcript:
1CHEM 5013 Applied Chemical Principles Chapters Three and Four (Mole Concepts)Professor BensleyAlfred State College
2Chapter Objectives Explain the concept of a mole in your own words. Interpret chemical equations in terms of both moles and molecules.Interconvert between mass, number of molecules, and number of moles.Determine a chemical formula from elemental analysis (i.e., from % compositions).
3Chapter ObjectivesDefine the concentration of a solution and calculate the molarity of solutions from appropriate data.Calculate the molarity of solutions prepared by dilution or calculate the quantities needed to carry out a dilution to prepare a solution of a specified concentration.Calculate the amount of product expected from a chemical reaction, given the amounts of reactants used.
4Chapter ObjectivesCalculate the amounts of reactants needed in a chemical reaction to produce a specified amount of product.Identify a limiting reagent and calculate the amount of product formed from a nonstoichiometric mixture of reactants.Calculate the percentage yield of a chemical reaction.
10A chemical mass unit, defined to be 6.022 x 1023 molecules, atoms, or some other unit.
11The Mole You have one car. How many engines do you have? How many wheels do you have?You have 1 dozen cars.How many dozens of engines do you have?How many dozens of wheels do you have?You have 1 mole of cars. (1 Chemist’s Dozen)How many moles of engines do you have?How many moles of wheels do you have?12 x6.02 x 1023 x
12The Mole You have one molecule of CCl4. How many Carbon atoms do you have?How many Chlorine atoms do you have?You have 1 dozen molecules of CCl4.How many dozen Carbon atoms do you have?How many dozen Chlorine atoms do you have?You have 1 mole of CCl4. (Chemist’s Dozen)How many moles of Carbon atoms do you have?How many moles of Chlorine atoms do you have?12 x6.02 x 1023 X
13The MoleExample: One mole of Na2CO3 contains how many moles of Sodium ions? How many actual sodium ions?How many moles of carbonate ions? How many actual carbonate ions? Think of it as (CO3)1
14The Mole 1 Mole of Oxygen atoms (O) contains how many O atoms? But 1 mole of Oxygen molecules (O2) contains how many O atoms?
15Molar MassMolar mass:What is molar mass of carbon-12? How many grams in one mole?Molar mass in grams per mole is numerically equal to the formula weight in amu.
16ExamplesHow many molecules of HNO3 are present in 2.5 moles HNO3?What is the mass in grams of one nitric acid molecule, HNO3?
17Mole Calculations Two VERY important mole calculations: How much does a given number of moles of a substance weigh?(convert moles to grams)Also, how many moles are in a given mass of a substance?(convert grams to moles)
18Mole CalculationsA sample of nitric acid contains mol HNO3. How many grams is this?A mixture for an acid used on a construction project calls for 25 grams of Sulfuric Acid (H2SO4) to be used. How many moles of sulfuric acid is this?
19Mole CalculationsThe formulation for a test batch of structural steel contains 0.05% Silicon by mass. This calculates out to 1.0x10-6 gram for your formulation. How many atoms of Silicon were added to the batch to produce the correct steel formulation?
20Determining Chemical Formulas Percent composition of a compound =Mass percentage:# grams of A in 100 g of the whole thingmass of A in the wholeMass %A = 100 x mass of the whole
21ExampleLead(II) chromate, PbCrO4 is used as a paint pigment (yellow). What is the percentage composition of lead(II) chromate?
22ExampleThe chemical name of table sugar is sucrose, C12H22O11. How many grams of carbon (C) are there in 61.8 grams of sucrose?
23Determining Chemical Formulas Empirical formula:Example: H2O2
24ExampleSodium pyrophosphate is used in detergent preparations. The mass percentages of the elements in this compound are 34.6% Na, 23.3% P, 42.1% O. What is the empirical formula of sodium pyrophosphate?
25Molecular Formula from Empirical Formula Need 2 things to determine MF:Molecular weight = n x empirical formula weightSo, n = molecular weightempirical formula weight
26ExampleHexamethylene is one of the materials used to produce a type of nylon. Elemental analysis of the substance gives 62.1% C, 13.8% H and 24.1% N. Its molecular weight is 116 amu. What is its molecular formula?
28Stoichiometry N2 (g) + 3H2 (g) 2NH3 (g) H2 molecules to produce N2 molecules react withH2 molecules to produceNH3 moleculesof N2 reacts withof H2 to produceof NH3
29Stoichiometry N2 (g) + 3H2 (g) 2NH3 (g) Because moles can be converted to grams, can also say:How many grams of nitrogen will react with 6.0 grams of hydrogen?
30balanced chemical equation!!! StoichiometryThe number of moles involved in a reaction is proportional to the coefficients in thebalanced chemical equation!!!
31Example How many moles of NH3 could we obtain from 3 moles of H2? How many moles of NH3 could we obtain from 4.8 mol H2?
32Stoichiometry N2 (g) + 3H2 (g) 2NH3 (g) Can also calculate problems involving masses of reactants or productsN2 (g) + 3H2 (g) 2NH3 (g)How much hydrogen (in kg) is needed to yield 907 kg of ammonia?
33Flow Chart for ANY Stoichiometry Problem Grams of AXConversion Factor:grams A to mol AFlow Chart for ANY Stoichiometry ProblemXConversion Factor:mol A to mol BXConversion Factor:mol B to grams BGrams of B
34ExampleHow many grams of HCl are required to react with 5.00 grams of manganese dioxide according to the equation?
35Limiting Reagent What happens when we don’t exactly follow the recipe? What happens when the L.R. is used up?So what determines the number of moles (amount) of product that we can obtain in a reaction?
36Limiting Reagent100 seats and 300 tires. How many bicycles can you make?1 seat + 2 tires 1 bicycleThe are the limiting reagent
37Limiting ReagentIf 0.30 mol Zn is added to hydrochloric acid containing 0.52 mol HCl, how many moles of H2 are produced?
38Limiting ReagentUrea, CH4N2O, is used as a nitrogen fertilizer. It is manufactured from ammonia and carbon dioxide.2NH3 + CO2 CH4N2O + H2O10.0g NH3 and 10.0g CO2 are reacted together. What is the maximum quantity (in grams) of urea than can be obtained?
40Working with Solutions Molar concentration or MolarityMoles of soluteLiters of solutionMolarity (M) =
41Molarity0.200 M (0.200 molar) solution of HCl is how many moles of HCl dissolved in 1 liter of water? How many grams of HCl dissolved in 1 liter of water?Example:You place a 1.53 gram sample of potassium dichromate, K2Cr2O7, into a 50.0 mL volumetric flask and add water to bring the solution up to the mark on the neck of the flask. What is the molarity of the solution?
42ExampleA solution of sulfuric acid (H2SO4) has a concentration of M.How many moles of sulfuric acid are contained in a 500 mL bottle of the solution?How many grams of sulfuric acid are in the 500 mL solution?
43Diluting Solutions You have a 10 M solution of HCl. Suppose however, you want a 1 M solution.How do we make this 1 M solution of HCl?Dilution formula derivation
44Diluting SolutionsA stock solution of concentrated hydrochloric acid is 12.1M. How much of this stock solution is needed to prepare 1.00 L of an aqueous solution, which is 0.25M HCl?