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Chapter 3
Stoichiometry: Chemical Calculations
3.1
Title
 Two views of the combination of carbon and oxygen to form carbon dioxide
Caption
 At the microscopic (molecular) level, chemical reactions occur between atoms and molecules (top) but we can show only a few atoms and molecules to represent the enormous numbers that actually make up the samples. In reality, we usually observe substances at the macroscopic level, and the artist's sketch of the substances at tha level represents one mole each (Avogadros's number) of C atoms, O2 molecules, and CO2 molecules.
Keywords
 model, chemical reaction
3.3
Title
 Flowchart for determining mass and related quantities from the number of moles of a substance
Caption
 Some problems require that you consider only the factors in steps 2Ð5; others require steps 1 and/or 6 as well.
Keywords
 flowchart, stoichiometry, mole, problem solving
3.4
Title
 Flowchart for determining the number of moles and related quantities from the mass of a substance
Caption
 Some problems require that you consider only the factors in steps 2Ð6; others require steps 1 and/or 7 as well.
Keywords
 flowchart, stoichiometry, mole, problem solving
3.4.1
Title
 Determining the mass % of carbon in butane, C4H10
Caption
 To determine the mass percent of an element in a substance, is is necessary do first determine the number of grams of that element in a mole of the molecule. The mass of carbon in butane, C4H10 is shown, using the flowchart steps 1-5 in Figure 3 to determine the mass of both carbon and hydrogen in butane.
Keywords
 problem solving, mass percent, stoichiometry, chemical formula
3.5
Title
 Apparatus for combustion analysis
Caption
 Oxygen gas enters the combustion apparatus and streams over the sample under analysis in a high-temperature furnace. The absorbers collect the water vapor and carbon dioxide that are produced in the combustion.
Keywords
 combustion, analysis, stoichiometry
3.7
Title
 Balancing the chemical equation for the reaction of hydrogen w/oxygen to form water
Caption
 (a) An incorrect way to balance the chemical equation for the reaction of hydrogen with oxygen to form water is shown. There is no evidence for the presence of atomic oxygen as a product. A reactant or product with a different chemical formula cannot be introduced for the purpose of balancing an equation.(b) Another incorrect way to balance the equation is shown. The product of the chemical reaction is water, H2O, not hydrogen peroxide, H2O2. A formula cannot be changed in order to balance a chemical equation.(c) The correctly balanced equation is shown. An equation ban be balanced only through the use of correct formulas and coefficients.
Keywords
 stoichiometry, balancing chemical equations, chemical reactions
3.8
Title
 Concept of equivalence, parallel parking model
Caption
 With parallel parking, each automobile is equivalent to 25 ft of curb space; that is, 1 automobile= 25 ft.
Keywords
 equivalence, dimensional analysis, model
3.9
Title
 Outline of reaction stoichiometry
Caption
 The substances A and B are two reactans, a reactant and a product, or two products of a chemical reaction.
Keywords
 flowchart, stoichiometry, problem solving
3.10
Title
 Molecular view of the reactants in the reaction between ethylene & bromine
Caption
 Ethylene (shown by the black and gray model) and bromine (orange) react in a 1:1 mole ratio. The reaction equation is: C2H4(g) + Br2(g) --> C2H4Br2(g)Here, ethylene moecules outnumber bromine molecules. Thus, ethylene is prsent in excess, and bromine is the limiting reactant.
Keywords
 reaction, model, ethylene, bromine, limiting reactant, limiting reagent
3.11
Title
 An analogy to determining a limiting reactant
Caption
 (a) To package the snack meal shown on the right requires sandwiches, cookies, and oranges in the ratio 1:2:1. Cookies are the "limiting reactant" for the situation shown in (b).
Keywords
 reaction, limiting reactant, limiting reagent, model, stoichiometry
3.14
Title
 Dilution of a solution
Caption
 When additional solvent is added to a concentrated solution (left), the number of solute molecules per unit volume of the solution decreases (right). That is, a larger volume of of the dilute solution is required to contain all the solute molecules than of the concentrated solution.
Keywords
 solution, dilution, concentration
3.15
Title
 Dilution of a copper(II) sulfate solution, Ex.26
Caption
 When a copper (II) sulfate solution is diluted by addition of solvent, the solute becomes more dilute. This is shown in the model as more "space" between the solute molecules.
Keywords
 solution, dilution, model
3.15.4P.24
Title
 Trimethobenzamide
Caption
 Trimethobenzamide is shown as a spacefill model.
Keywords
 model, spacefill, Trimethobenzamide, molecular structure
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