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Now, invoking the condition that the system is in equilibrium, that is, the chemical potential of the adsorbed molecules is equal to that of the molecules in gas phase, we have An example plot of the surface coverage θ A = P/(P + P 0) with respect to the partial pressure of the adsorbate. P 0 = 100 mTorr.
This dependence on microscopic variables is the central point of statistical mechanics. With a model of the microscopic constituents of a system, one can calculate the microstate energies, and thus the partition function, which will then allow us to calculate all the other thermodynamic properties of the system.
Δ r G°, Gibbs free energy change per mole of reaction for unmixed reactants and products at standard conditions (i.e. 298 K, 100 kPa, 1 M of each reactant and product), R, gas constant, T, absolute temperature, ln, natural logarithm, Q r, reaction quotient (unitless), K eq, equilibrium constant (unitless),
Likewise, it is used to calculate lipophilic efficiency in evaluating the quality of research compounds, where the efficiency for a compound is defined as its potency, via measured values of pIC 50 or pEC 50, minus its value of log P. [27] Drug permeability in brain capillaries (y axis) as a function of partition coefficient (x axis) [28]
In simple words, we can say that the partial pressure of a gas in vapour phase is directly proportional to the mole fraction of a gas in solution. An example where Henry's law is at play is the depth-dependent dissolution of oxygen and nitrogen in the blood of underwater divers that changes during decompression , going to decompression sickness .
K a is variously named a dissociation constant, [3] an acid ionization constant, [2]: 668 an acidity constant [1] or an ionization constant. [ 2 ] : 708 It serves as an indicator of the acid strength: stronger acids have a higher K a value (and a lower p K a value).
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
When a temperature is reached such that the sum of the equilibrium vapor pressures of the liquid components becomes equal to the total pressure of the system (it is otherwise smaller), then vapor bubbles generated from the liquid begin to displace the gas that was maintaining the overall pressure, and the mixture is said to boil.