Skip to main content
Ch.18 - Chemistry of the Environment
Brown - Chemistry: The Central Science 15th Edition
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoBrown 15th EditionCh.18 - Chemistry of the EnvironmentProblema 74b
Capitolo 18, Problema 74b

he concentration of H2O in the stratosphere is about 5 ppm. It undergoes photodissociation according to:


H2O(𝑔)⟶H(𝑔)+OH(𝑔)


b.Given that the average bond enthalpy for an O−H bond is 463 kJ/mol, calculate the maximum wavelength for a photon that could cause this dissociation.

Guida verificata passo dopo passo
1
Identify the energy required to break one mole of O-H bonds, which is given as 463 kJ/mol.
Convert the energy from kJ/mol to J/mol by multiplying by 1,000 (since 1 kJ = 1,000 J).
Use the formula for energy of a photon: E = h * c / λ, where E is the energy in joules, h is Planck's constant (6.626 x 10^-34 J·s), c is the speed of light (3.00 x 10^8 m/s), and λ is the wavelength in meters.
Rearrange the formula to solve for wavelength (λ): λ = h * c / E.
Substitute the values for h, c, and the energy (in J/mol) into the equation to calculate the maximum wavelength in meters.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
9m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Photodissociation

Photodissociation is a process in which a chemical compound breaks down into its constituent atoms or simpler molecules upon absorbing light (photons). In the context of the given question, water vapor (H2O) in the stratosphere can absorb ultraviolet light, leading to the dissociation into hydrogen (H) and hydroxyl (OH) radicals. Understanding this concept is crucial for analyzing how light interacts with molecules and the energy required for such reactions.

Bond Enthalpy

Bond enthalpy, or bond dissociation energy, is the amount of energy required to break a specific bond in a molecule in the gas phase. For the O−H bond in water, the average bond enthalpy is given as 463 kJ/mol. This value is essential for calculating the energy of the photon needed to cause the dissociation of water, as it directly relates to the energy required to break the bonds holding the molecule together.
Video consigliato:
Percorso guidato
02:34
Enthalpy of Formation

Photon Energy and Wavelength Relationship

The energy of a photon is inversely related to its wavelength, described by the equation E = hc/λ, where E is energy, h is Planck's constant, c is the speed of light, and λ is the wavelength. To find the maximum wavelength that can cause the dissociation of H2O, one must rearrange this equation to solve for λ using the bond enthalpy as the energy input. This relationship is fundamental in understanding how light can induce chemical reactions.
Video consigliato:
Percorso guidato
00:31
Frequency-Wavelength Relationship
Pratica correlata
Domanda del libro di testo

(b) Concentrations of lead in the bloodstream are often quoted in units of μg/dL. Averaged over the entire country, the mean concentration of lead in the blood was measured to be 1.6 μg/dL in 2008. Express this concentration in ppb.

378
views
Domanda del libro di testo

In 1986 an electrical power plant in Taylorsville, Georgia, burned 8,376,726 tons of coal, a national record at that time. (a) Assuming that the coal was 83% carbon and 2.5% sulfur and that combustion was complete, calculate the number of tons of carbon dioxide and sulfur dioxide produced by the plant during the year.

1470
views
Domanda del libro di testo

The water supply for a midwestern city contains the following impurities: coarse sand, finely divided particulates, nitrate ions, trihalomethanes, dissolved phosphorus in the form of phosphates, potentially harmful bacterial strains, dissolved organic substances. Which of the following processes or agents, if any, is effective in removing each of these impurities: coarse sand filtration, activated carbon filtration, aeration, ozonization, precipitation with aluminum hydroxide?

406
views
Domanda del libro di testo

The following data were collected for the desturction of O3 by H (O3 + H → O2 + OH) at very low concentrations (b) Calculate the rate constant

324
views