Back
Problem 1
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 AB3Problem 2
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, 3Problem 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
Problem 6
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 kgProblem 7
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 8
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
Problem 9
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) 34.1Problem 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
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%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
Problem 13
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) C4H10O2Problem 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
Problem 15
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) oxideProblem 27
Which of the following drawings is more likely to represent an ionic compound and which a covalent compound? (a)Problem 28
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 30
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 31
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 32
The following diagram represents the reaction of A2 (red spheres) with B2 (blue spheres):
(a) Write a balanced equation for the reaction, and identify the limiting reactant. (b) How many moles of product can be made from 1.0 mol of A2 and 1.0 mol of B2?
Problem 33
What is the percent composition of cysteine, one of the 20 amino acids commonly found in proteins? (Gray = C, red = O, blue = N, yellow = S, ivory = H.)Problem 34
What is the difference between a covalent bond and an ionic bond?
Problem 34
Cytosine, a constituent of deoxyribonucleic acid (DNA), can be represented by the following molecular model. If 0.001 mol of cytosine is submitted to combustion analysis, how many moles of CO2 and how many moles of H2O would be formed? (Gray = C, red = O, blue = N, ivory = H.)Problem 35
A hydrocarbon of unknown formula CxHy was submitted to combustion analysis with the following results. What is the empirical formula of the hydrocarbon?
Problem 36
Which of the following equations is balanced?
(a) The development reaction in silver-halide photography: 2 AgBr + 2 NaOH + C6H6O2 → 2 Ag + H2O + 2 NaBr + C6H4O2
(b) The preparation of household bleach: 2 NaOH + Cl2 → NaOCl + NaCl + H2O
Problem 37a
Which of the following equations is balanced? Balance any that need it. (a) The thermite reaction, used in welding: Al + Fe2O3 → Al2O3 + Fe
Problem 38a
Balance the following equations. (a) Mg + HNO3 → H2 + Mg(NO3)2
Problem 38b
Balance the following equations. (b) CaC2 + H2O → Ca(OH)2 + C2H2
Problem 38c
Balance the following equations. (c) S + O2 → SO3
Problem 38d
Balance the following equations. (d) UO2 + HF → UF4 + H2O
