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Ch.3 - Mass Relationships in Chemical Reactions

Chapter 3, Problem 11

What is the percent composition by mass of Mn in potas-sium permanganate, KMnO4? (LO 3.10) (a) 22.6% (b) 34.8% (c) 49.9% (d) 54.9%

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Hi everyone here we have a question telling us in a nickel cadmium battery. Academy in metal is used in the an ode. And nikola oxy hydroxide is at the cathode. And the question is, what is the mass percent of nickel and nickel oxy hydroxide? So mass percent equals the mass of an element over the mass of the compound times 100. So the molar mass of nickel oxy hydroxide consists of nickel, Which is 58. 34 g per mole oxygen, Which is 16.0 g per mole hydrogen, Which is 1.008 g per mole. So Nicole oxy hydroxide equals .6934 g per mole Plus 16.0 g per mole Times two. Because there's two oxygen's Plus 1.008 g per mole. And that equals 91. grams per mole. So our mass percent equals .6934g Permal divided by 91. g per mole times two equals 64.0%. And that is our final answer. Thank you for watching. Bye.
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The diagram represents a mixture of AB2 and B2 before it reacts to form AB3. (Red spheres = A, blue spheres = B.) Which reactant is limiting, and how many AB3 molecules are formed? (LO 3.7)

(a) B2 is limiting, and 10 molecules of AB3 are formed. (b) B2 is limiting, and 4 molecules of AB3 are formed. (c) AB2 is limiting, and 6 molecules of AB3 are formed. (d) AB2 is limiting, and 4 molecules of AB3 are formed
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If 2.00 moles of nitrogen and 5.50 moles of hydrogen are placed in a reaction vessel and react to form ammonia, what is the theoretical yield of ammonia (NH3)? (LO 3.8) N2(g) + 3 H2(g) --> 2 NH3(g) (a) 31.2 g (b) 62.3 g (c) 93.7 g (d) 34.1
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Silver sulfide, the tarnish on silverware, comes from the reaction of silver metal with hydrogen sulfide (H2S).The unbalanced equation is: Ag + H2S + O2 --> Ag2S + H2O Unbalanced If the reaction was used intentionally to prepare Ag2S, how many grams would be formed from 496 g of Ag, 80.0 g of H2S, and excess O2 if the reaction takes place in 90% yield? (LO 3.9) (a) 525 g (b) 1139 g (c) 583 g (d) 1025

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Textbook Question
Lactic acid forms in muscle tissue after strenuous exercise. Elemental analysis shows that lactic acid is 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen by mass. If the molec-ular weight of lactic acid is 90.08, what is the molecular for-mula? (LO 3.11) (a) CH2O (b) C3H6O3 (c) C4H8O4 (d) C4H10O2
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Combustion analysis is performed on 0.50 g of a hydrocar-bon and 1.55 g of CO2, and 0.697 g of H2O are produced. The mass spectrum for the hydrocarbon is provided below. What is the molecular formula? (LO 3.12 and 3.13)

(a) C5H11 (b) C8H18 (c) C11H10 (d) C10H22

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