Textbook Question
Consider the reaction 2 H2(g) + O2(g) → 2 H2O(l). (a) Use the bond enthalpies in Table 5.4 to estimate H for this reaction, ignoring the fact that water is in the liquid state.
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Ch.5 - Thermochemistry
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement177
- Ch.2 - Atoms, Molecules, and Ions231
- Ch.3 - Chemical Reactions and Reaction Stoichiometry216
- Ch.4 - Reactions in Aqueous Solution189
- Ch.5 - Thermochemistry175
- Ch.6 - Electronic Structure of Atoms168
- Ch.7 - Periodic Properties of the Elements150
- Ch.8 - Basic Concepts of Chemical Bonding177
- Ch.9 - Molecular Geometry and Bonding Theories200
- Ch.10 - Gases179
- Ch.11 - Liquids and Intermolecular Forces113
- Ch.12 - Solids and Modern Materials154
- Ch.13 - Properties of Solutions157
- Ch.14 - Chemical Kinetics199
- Ch.15 - Chemical Equilibrium128
- Ch.16 - Acid-Base Equilibria164
- Ch.17 - Additional Aspects of Aqueous Equilibria163
- Ch.18 - Chemistry of the Environment105
- Ch.19 - Chemical Thermodynamics164
- Ch.20 - Electrochemistry171
- Ch.21 - Nuclear Chemistry122
- Ch.22 - Chemistry of the Nonmetals82
- Ch.23 - Transition Metals and Coordination Chemistry79
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry16
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 5, Problem 90b
(b) A particular chip snack food is composed of 12% protein, 14% fat, and the rest carbohydrate. What percentage of the calorie content of this food is fat?
Verified step by step guidance1
Step 1: Understand the problem. We need to find the percentage of the calorie content that comes from fat in the snack food.
Step 2: Recall the caloric values for macronutrients. Protein and carbohydrates each provide 4 calories per gram, while fat provides 9 calories per gram.
Step 3: Assume a certain total mass of the snack food for simplicity, such as 100 grams. This makes it easy to calculate the mass of each macronutrient: 12 grams of protein, 14 grams of fat, and 74 grams of carbohydrates.
Step 4: Calculate the total calories from each macronutrient. Multiply the mass of each macronutrient by its respective caloric value: protein (12g x 4 cal/g), fat (14g x 9 cal/g), and carbohydrates (74g x 4 cal/g).
Step 5: Determine the percentage of calories from fat. Divide the calories from fat by the total calories from all macronutrients, then multiply by 100 to get the percentage.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Caloric Content of Macronutrients
Different macronutrients provide varying amounts of calories per gram: proteins and carbohydrates each provide 4 calories per gram, while fats provide 9 calories per gram. Understanding these values is essential for calculating the contribution of each macronutrient to the total caloric content of a food item.
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Percentage Composition
The percentage composition of a food item indicates the proportion of each macronutrient relative to the total mass. In this case, knowing that the snack is 12% protein, 14% fat, and the remainder carbohydrates allows us to determine the total percentage of calories derived from fat in relation to the overall caloric content.
Total Caloric Calculation
To find the percentage of calorie content from fat, one must first calculate the total calories from each macronutrient based on their percentages and caloric values. Then, the calories from fat can be divided by the total calories to find the percentage contribution of fat to the overall caloric content of the snack.
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