Basic Processes and Osmosis
(Solution, Evaporation, Diffusion and Osmosis)

concentration gradient - change in concentration of a solute across distance, as a gradient within a cell or across a membrane; if molecules are free to move, they will diffuse along the gradient from higher to lower concentrations.

dialysis - the separation of molecules of different types from heterogeneous, dissolved or suspended substances.

diffusion - the process by which molecules move through their kinetic energy from an area of higher concentration to an area of lower concentration.

dissolving - the process by which a substance breaks apart into distinct particles (atoms, molecules, or ions) upon encountering or being placed in a solvent.

distinguishing features - the most important, salient features of a concept, those that distinguish that concept from other closely related concepts and those that provide context for the concept (what is it part of?, what are its parts?, what does it do?, what does it require?, etc.)

empty space - this is what is in between atoms or molecules of any substance; there is also a lot of empty space within atoms and molecules.

entropy - the measure of randomness or disorder of a system; in chemical reactions and molecular processes, spontaneous progress is always made in a direction which will increase the total state of disorder; as an analogy, throwing a bundle of confetti in the air will result in many isolated pieces scattered all over the ground, not the single bundle from which the pieces originated.

evaporating - the process by which molecules of a liquid change state and become molecules of a gas; the molecules themselves remain unchanged; the speed of the molecules and the space between them increases significantly.

hypertonic - having a higher concentration of solutes compared to another solution.

hypotonic - having a lower concentration of solutes compared to another solution.

isotonic - two solutions having the same concentrations of solutes.

osmosis - the diffusion of water through a semipermeable membrane from an area of higher concentration of water to an area of lower concentration of water.

saturated solution - condition when a solvent contains so much dissolved solute that no more solute can be dissolved without adding more solvent or increasing the temperature.

saturation point - that concentration of solute in a solvent at which no more solute can go into solution; saturation point increases with increasing temperature.

semipermeable membrane - a physical barrier which only allows certain particles (based on size and charge) to pass through it; membranes of organelles and cells are semipermeable membranes through which small, uncharged molecules such as water, oxygen and carbon dioxide pass freely.

solute - a substance that has been dissolved or could be dissolved in another substance (solvent).

solution - a homogeneous substance formed when one substance (solute) has been dissolved in another (solvent).

solvent - a substance capable of dissolving other substances.