According to Problem 17.43, the rate with which oxygen...

According to Problem 17.43, the rate with which oxygen molecules strike a surface at 1 bar and $25^{\circ} \mathrm{C}$ is $2.69 \times$ $10^{23} \mathrm{cm}^{-2} \mathrm{s}^{-1} .$ If the oxygen molecules are striking a platinum surface, what are the frequencies of collisions per atom on the $(100),(110), \text { and }(111) \text { planes? (See Problem } 23.32 .)$

Key Concepts

Collision Frequency per Atom

Collision frequency per atom is obtained by dividing the molecular flux by the surface atomic density. This metric quantifies the average number of molecular impacts an individual atom experiences per unit time, making it an important concept in surface kinetics and catalysis studies.

Crystallographic Planes

Crystallographic planes refer to the specific orientations and arrangements of atoms in a crystal lattice. In the context of collision frequency calculations, the particular plane (such as (100), (110), or (111)) determines how densely packed the surface atoms are, which in turn influences the number of collisions each atom experiences.

Surface Atomic Density

Surface atomic density is the number of atoms present per unit area on a surface, which depends on the lattice structure and the specific crystallographic plane. It is a crucial factor when converting the total molecular flux on a surface to the collision frequency per individual atom.

Molecular Flux

Molecular flux is defined as the number of particles striking a unit area of a surface per unit time. It is a key parameter in kinetic theory and relates macroscopic gas properties (like pressure and temperature) to microscopic collision events on surfaces, allowing one to calculate how many molecules impact the surface per second per square centimeter.

Kinetic Theory of Gases

Kinetic theory of gases connects the temperature, pressure, and molecular mass of a gas with the motions of its molecules. This theory underpins the calculation of molecular flux by using principles such as the Maxwell?Boltzmann distribution, which describes the spread of speeds (and hence, kinetic energies) among gas molecules.

Transcript

Please give Ace some feedback