| | CONCEPTS OF CHEMICAL PROCESSES (2) |
| |
|
| | See Concept Map
|
| 7 | In the case of an incompressible liquid at rest (at constant temperature), the chemical potential depends only on the pressure of the liquid. |
| 8 | If concentrations are not too high, the chemical potential of a substance depends logarithmically upon its concentration. |
| 9 | A transformation running by itself typically ends in a state of equilibrium. Close to the final state, the reaction rate or flow rate is proportional to the chemical potential difference of the substances and to the concentrations of the substances. |
| 10 | In chemical equilibrium (involving flow or transformation), the difference of chemical potentials of the substances taking part in the processes is equal to zero. As a result, the substances have well-defined concentrations at given pressures and temperatures (their ratios are described by the so-called equilibrium constant). |
| 11 | Substances can flow through materials by themselves from points of high to points of low concentration. This is called diffusion. In diffusion, the current of amount of substances is proportional to the gradient of the chemical potential and to the concentration. As a result, in a uniform material, the current is proportional to the gradient of concentration. |
| 12 | If a substance flows from one environment into another, the flow depends upon the difference of chemical potentials of the substance in the two environments. In equilibrium, concentrations do not need to be equal. |
| 13 | Dissolved substances behave like simple gases—they have a pressure proportional to their concentration. As a result, a substance dissolved in a solvent reduces the pressure—and therefore the chemical potential—of the solvent. (Salt in water reduces the chemical potential of water; if salt water is separated from fresh water by a semi-permeable membrane, water flows from fresh water to salt water: this phenomenon is called osmosis.) |
| |
|
| | 1 | 2
|