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Ch.5 - Thermochemistry
Brown - Chemistry: The Central Science 15th Edition
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Brown 15th EditionCh.5 - Thermochemistry문제 121b
5장, 문제 121b

At 20 °C (approximately room temperature) the average velocity of N2 molecules in air is 1050 mph. (b) What is the kinetic energy (in J) of an N2 molecule moving at this speed?

검증된 단계별 안내
1
Convert the velocity of the N2 molecule from miles per hour (mph) to meters per second (m/s) using the conversion factor: 1 mph = 0.44704 m/s.
Calculate the mass of an N2 molecule. The molecular weight of N2 is approximately 28 g/mol. Convert this mass to kilograms (kg) by using the conversion factor: 1 g = 0.001 kg. Then, use Avogadro's number (6.022 \(\times\) 10^{23} molecules/mol) to find the mass of one molecule.
Use the kinetic energy formula: KE = \(\frac{1}{2}\)mv^2, where 'm' is the mass of the molecule in kg and 'v' is the velocity in m/s.
Plug the values of 'm' and 'v' into the kinetic energy formula to calculate the kinetic energy of the N2 molecule.
Ensure the final kinetic energy value is in Joules (J), as this is the standard unit for energy in the International System of Units (SI).

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주요 개념

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

Kinetic Energy

Kinetic energy is the energy possessed by an object due to its motion, calculated using the formula KE = 0.5 * m * v², where m is the mass of the object and v is its velocity. For gas molecules like N₂, this concept is crucial for understanding how speed translates into energy at the molecular level.
추천 영상:
가이드 코스
00:34
Kinetic & Potential Energy

Molecular Mass

The molecular mass of a substance is the mass of a single molecule, typically expressed in atomic mass units (amu). For nitrogen (N₂), the molecular mass is approximately 28 amu, which is essential for calculating the kinetic energy of an individual N₂ molecule when given its velocity.
추천 영상:
가이드 코스
02:19
Atomic Mass

Conversion of Units

In physics and chemistry, it is often necessary to convert units to ensure consistency in calculations. In this case, converting the speed from miles per hour (mph) to meters per second (m/s) is essential for using standard SI units in the kinetic energy formula, allowing for accurate energy calculations.
추천 영상:
가이드 코스
01:56
Conversion Factors
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Consider two solutions, the first being 50.0 mL of 1.00 M CuSO4 and the second 50.0 mL of 2.00 M KOH. When the two solutions are mixed in a constant-pressure calorimeter, a precipitate forms and the temperature of the mixture rises from 21.5 to 27.7 °C. (a) Before mixing, how many grams of Cu are present in the solution of CuSO4?

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교과서 질문

Depending on their specific usage, fuels are judged in part on energy released per unit volume and energy released per unit mass. Three prospective fuels are listed in the following table, along with their densities and molar enthalpies of combustion.

a. Rank the three fuels according to their enthalpy produced per gram.

b. Rank them according to their enthalpy produced per cm3:

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