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- The reaction of A2 (red spheres) with B2 (blue spheres) is shown in the diagram. What is the balanced chemical equa-tion? (LO 3.1) (a) 2 A2 + 6 B2 ---> 4 AB3 (b) 4 A + 12 B ---> 4 AB3 (c) 4 A + 12 B ---> A4 + B12 (d) A2 + 3 B2 ---> 2 AB3
Problem 1
- What are the coefficients in the balanced equation for the combustion of ethanol? (LO 3.2) (a) 1, 3, 2, 3 (b) 2, 3, 4, 3 (c) 2, 7, 4, 6 (d) 1, 4, 2, 3
Problem 2
Problem 3
The ball-and-stick molecular model is a representation of caf-feine. Calculate the molecular weight of caffeine. (Gray = C, red = O, blue = N, ivory = H.) (LO 3.3)
(a) 194.2 (b) 182.2 (c) 192.2 (d) 180.2
Problem 4
A can of diet soda contains 180 mg of the low-calorie sugar substitute aspartame (C14H18N2O5). How many molecules of aspartame are in the can of soda? (LO 3.4) (a) 3.7 * 10^23 (b) 3.7 * 10^20 (c) 3.2 * 10^25 (d) 1.2 * 10^22
Problem 5
How many moles of chloride ions are in 7.75 g of FeCl3? (LO 3.4) (a) 4.78 * 10^-2 (b) 1.59 * 10^-2 (c) 1.43 * 10^-1 (d) 1.91 * 10^-1
- One way to make coal burning better for the environment is to remove carbon dioxide from the exhaust gases released from power plants using a compound containing an amine (-NH2) group. The reaction between carbon dioxide and monoethanolamine is: CO2(g) + 2 HOCH2CH2NH2(aq) -> HOCH2CH2NH3 +(aq) + HOCH2CH2NHCO2-(aq) What mass of monoethanoloamine is required to react with 1.0 kg of carbon dioxide? (LO 3.5) (a) 2.8 kg (b) 1.1 kg (c) 0.93 kg (d) 0.53 kg
Problem 6
- If 42.85 grams of salicylic acid reacts with excess acetic anhydride and produces 48.47 grams of aspirin, what is the percent yield of the reaction? (LO 3.6) (a) 88.40% (b) 64.69% (c) 86.72% (d) 78.74%
Problem 7
- 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)
Problem 8
(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
- 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
Problem 9
Problem 10
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
- 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%
Problem 11
Problem 12
Dimethylhydrazine, a colorless liquid used as a rocket fuel, is 40.0% C, 13.3% H, and 46.7% N. What is the empirical formula? (LO 3.11) (a) CH4N9 (b) CH2N (c) C2H4N (d) C2H5N2
- 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
Problem 13
Problem 14
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
- Which of the following compounds is incorrectly named? (LO 2.23–2.25) (a) CaO; calcium oxide (b) FeBr2; iron dibromide (c) N2O5; dinitrogen pentoxide (d) CrO3; chromium(VI) oxide
Problem 15
- Which of the following drawings is more likely to represent an ionic compound and which a covalent compound? (a)
Problem 27
- Each of the pictures (a)–(d) represents one of the following substances at 25 °C: sodium, chlorine, iodine, sodium chloride. Which picture corresponds to which substance? (a)
Problem 28
- The diagrams represent a reaction on the molecular level. Atoms of A are represented with red spheres, and atoms of B are represented with blue spheres. Write a balanced chemical equation.
Problem 30
- Fluoxetine, marketed as an antidepressant under the name Prozac, can be represented by the following ball-and-stick molecular model. Write the molecular formula for fluoxetine, and calculate its molecular weight. (Red = O, gray = C, blue = N, yellow green = F, ivory = H.)
Problem 31