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.
499
views
Ch.5 - Thermochemistry
Chapter 5, Problem 95
The heat of combustion of fructose, C6H12O6, is -2812 kJ/mol. If a fresh golden delicious apple weighing 4.23 oz (120 g) contains 16.0 g of fructose, what caloric content does the fructose contribute to the apple?
Verified step by step guidance1
Convert the mass of fructose from grams to moles using its molar mass. The molar mass of fructose (C_6H_{12}O_6) is calculated as follows: (6 \times 12.01) + (12 \times 1.01) + (6 \times 16.00) g/mol.
Use the moles of fructose to calculate the total energy released during combustion using the given heat of combustion value (-2812 kJ/mol).
Convert the energy from kilojoules to calories. Remember that 1 calorie = 4.184 joules, so you will need to convert kilojoules to joules first.
Convert the energy from calories to kilocalories (food calories), as nutritional information is typically given in kilocalories. Note that 1 kilocalorie = 1000 calories.
The final value represents the caloric content contributed by the fructose in the apple.
Verified Solution
Video duration:
2m
This video solution was recommended by our tutors as helpful for the problem above.Was this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Heat of Combustion
The heat of combustion is the amount of energy released when a substance is completely burned in oxygen. It is typically expressed in kilojoules per mole (kJ/mol). For fructose, the heat of combustion is -2812 kJ/mol, indicating that this amount of energy is released when one mole of fructose is oxidized.
Recommended video:
Guided course
02:24
Combustion Apparatus
Molar Mass
Molar mass is the mass of one mole of a substance, usually expressed in grams per mole (g/mol). For fructose (C6H12O6), the molar mass is approximately 180.18 g/mol. This value is essential for converting between grams of fructose and moles, which is necessary for calculating the energy content based on the heat of combustion.
Recommended video:
Guided course
02:11Molar Mass Concept
Caloric Content
Caloric content refers to the amount of energy provided by food, typically measured in calories or kilocalories. In this context, the caloric content contributed by fructose in the apple can be calculated by determining how many moles of fructose are present and multiplying by the heat of combustion, allowing us to express the energy contribution in familiar dietary terms.
Recommended video:
Guided course
06:35Effective Nuclear Charge Calculation with Slater's Rules
Related Practice
Textbook Question
(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?
1241
views
Textbook Question
(a) A serving of a particular ready-to-serve chicken noodle soup contains 2.5 g fat, 14 g carbohydrate, and 7 g protein. Estimate the number of Calories in a serving.
3
views
Textbook Question
The heat of combustion of ethanol, C2H5OH(l), is -1367 kJ/mol. A batch of Sauvignon Blanc wine contains 10.6% ethanol by mass. Assuming the density of the wine to be 1.0 g/mL, what is the caloric content due to the alcohol (ethanol) in a 6-oz glass of wine (177 mL)?
3
views
Textbook Question
The standard enthalpies of formation of gaseous propyne (C3H4), propylene (C3H6), and propane (C3H8) are +185.4, +20.4, and -103.8 kJ/mol, respectively. (b) Calculate the heat evolved on combustion of 1 kg of each substance.
597
views
Textbook Question
The standard enthalpies of formation of gaseous propyne (C3H4), propylene (C3H6), and propane (C3H8) are +185.4, +20.4, and -103.8 kJ/mol, respectively. (c) Which is the most efficient fuel in terms of heat evolved per unit mass?
1934
views