Textbook Question
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
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Ch.3 - Mass Relationships in Chemical Reactions
McMurry8th EditionChemistryISBN: 9781292336145
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Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement143
- Ch.2 - Atoms, Molecules & Ions134
- Ch.3 - Mass Relationships in Chemical Reactions149
- Ch.4 - Reactions in Aqueous Solution157
- Ch.5 - Periodicity & Electronic Structure of Atoms92
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory73
- Ch.7 - Covalent Bonding and Electron-Dot Structures47
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure51
- Ch.9 - Thermochemistry: Chemical Energy104
- Ch.10 - Gases: Their Properties & Behavior138
- Ch.11 - Liquids & Phase Changes43
- Ch.12 - Solids and Solid-State Materials56
- Ch.13 - Solutions & Their Properties98
- Ch.14 - Chemical Kinetics79
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Aqueous Equilibria: Acids & Bases94
- Ch.17 - Applications of Aqueous Equilibria125
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium66
- Ch.19 - Electrochemistry130
- Ch.20 - Nuclear Chemistry73
- Ch.21 - Transition Elements and Coordination Chemistry122
- Ch.22 - The Main Group Elements155
- Ch.23 - Organic and Biological Chemistry43
Chapter 3, Problem 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%
Verified step by step guidance1
Identify the balanced chemical equation for the reaction: \( \text{C}_7\text{H}_6\text{O}_3 + \text{C}_4\text{H}_6\text{O}_3 \rightarrow \text{C}_9\text{H}_8\text{O}_4 + \text{C}_2\text{H}_4\text{O}_2 \).
Calculate the molar mass of salicylic acid (\( \text{C}_7\text{H}_6\text{O}_3 \)) and aspirin (\( \text{C}_9\text{H}_8\text{O}_4 \)).
Determine the moles of salicylic acid used by dividing the given mass (42.85 grams) by its molar mass.
Use the stoichiometry of the balanced equation to find the theoretical yield of aspirin in grams.
Calculate the percent yield using the formula: \( \text{Percent Yield} = \left( \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \right) \times 100\% \), where the actual yield is 48.47 grams.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Percent Yield
Percent yield is a measure of the efficiency of a chemical reaction, calculated by comparing the actual yield of a product to the theoretical yield. It is expressed as a percentage and is determined using the formula: (actual yield / theoretical yield) × 100. A high percent yield indicates that the reaction proceeded effectively, while a low percent yield may suggest incomplete reactions or side reactions.
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Percent Yield in Reactions
Stoichiometry
Stoichiometry involves the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It allows chemists to predict the amounts of substances consumed and produced in a reaction. Understanding stoichiometry is essential for determining the theoretical yield, which is the maximum amount of product that can be formed from given amounts of reactants.
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Limiting Reactant
The limiting reactant is the substance that is completely consumed first in a chemical reaction, thus determining the maximum amount of product that can be formed. Identifying the limiting reactant is crucial for calculating the theoretical yield, as it dictates how much of the product can be produced based on the initial quantities of reactants. In this case, salicylic acid is the limiting reactant since it reacts with excess acetic anhydride.
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Related Practice
Textbook Question
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
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Textbook Question
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
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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Textbook Question
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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Textbook Question
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
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