Ch.5 - Thermochemistry

Brown - Chemistry: The Central Science 14th Edition

Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232당신이 사용하는 게 아니라요?교과서 변경

Brown 14th Edition

Ch.5 - Thermochemistry

문제 97

5장, 문제 97

At the end of 2012, global population was about 7.0 billion people. What mass of glucose in kg would be needed to provide 1500 Cal/person/day of nourishment to the global population for one year? Assume that glucose is metabolized entirely to CO₂(𝑔) and H₂O(𝑙) according to the following thermochemical equation: C₆H₁₂O₆(s) + 6 O₂(𝑔) → 6 CO₂(𝑔) + 6 H₂O(𝑙) ΔH° = -2803 kJ

검증된 단계별 안내

Calculate the total number of Calories needed for the global population for one year. Multiply the daily Caloric intake per person by the number of people and then by the number of days in a year.

Convert the total Caloric intake from Calories to kilojoules (kJ) knowing that 1 Calorie equals 4.184 kJ.

Use the thermochemical equation provided to determine the amount of energy produced by the combustion of glucose. Note that the combustion of one mole of glucose releases 2803 kJ.

Calculate the number of moles of glucose needed to meet the global energy requirement by dividing the total energy requirement (from step 2) by the energy released per mole of glucose (from step 3).

Convert the number of moles of glucose to mass in kilograms. Use the molar mass of glucose, which is approximately 180.16 g/mol, and convert grams to kilograms.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It allows us to determine the amount of a substance needed or produced in a reaction. In this question, stoichiometry will help calculate how much glucose is required to meet the caloric needs of the global population by using the provided thermochemical equation.

Caloric Conversion

Caloric conversion involves translating energy requirements, typically measured in calories, into a mass of a specific substance. In this case, we need to convert the daily caloric needs of the population into a total annual requirement and then relate that to the energy released from glucose metabolism. Understanding this conversion is essential for determining the mass of glucose needed.

Thermochemistry

Thermochemistry is the study of the heat energy associated with chemical reactions. The given thermochemical equation provides the enthalpy change (ΔH°) for the metabolism of glucose, indicating how much energy is released when glucose is completely oxidized. This information is crucial for calculating how much glucose is necessary to provide the required energy for the global population.

관련 실천

교과서 질문

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?

1938

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교과서 질문

It is interesting to compare the 'fuel value' of a hydrocarbon in a hypothetical world where oxygen is not the combustion agent. The enthalpy of formation of CF₄(g) is -679.9 kJ/mol. Which of the following two reactions is the more exothermic?

CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(g)

CH₄(g) + 4 F₂(g) → CF₄(g) + 4 HF(g)

854

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교과서 질문

The air bags that provide protection in automobiles in the event of an accident expand because of a rapid chemical reaction. From the viewpoint of the chemical reactants as the system, what do you expect for the signs of q and w in this process?

885

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교과서 질문

The automobile fuel called E85 consists of 85% ethanol and 15% gasoline. E85 can be used in the so-called flex-fuel vehicles (FFVs), which can use gasoline, ethanol, or a mix as fuels. Assume that gasoline consists of a mixture of octanes (different isomers of C₈H₁₈), that the average heat of combustion of C₈H₁₈(l) is 5400 kJ/mol, and that gasoline has an average density of 0.70 g/mL. The density of ethanol is 0.79 g/mL. (a) By using the information given as well as data in Appendix C, compare the energy produced by combustion of 1.0 L of gasoline and of 1.0 L of ethanol.

1969

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교과서 질문

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. (a) Calculate the heat evolved per mole on combustion of each substance to yield CO₂(g) and H₂O(g). (b) Calculate the heat evolved on combustion of 1 kg of each substance.

599

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