Describe the difference between concentrated and dilute at the molecular level??
Hard to know what you are after, but let's define
The typical description of
(here we have the quotient, moles of solute per MASS of solvent).
Depending on the problem you have, sometimes a value of
Solutions commonly form in the gas phase (including the air we breathe), and in the liquid phase. Solutions in the SOLID phase are also known, and a good example of these materials are
Anyway, to answer your question (FINALLY!), if we dilute a solution, effectively we add more solvent, more dispersing medium, and the denominator in the quotient becomes LARGER. And thus the concentration becomes SMALLER, whatever units you use. Capisce?
Well, at the 'molecular' level, I would describe it like so...
Take an aqueous solution as an example...
A more "concentrated" solution has the particles closer together than a less "concentrated" solution, i.e. there are more particles per unit volume, the most fundamental/general definition of concentration:
#"conc." = "Number of particles"/"unit volume"#
To dilute the solution, it is easiest to add solvent.
The solvent surrounds the solute particles, literally separating them from each other.
The more solvent there is, the more segregated the solute particles become (the harder it is for them to find each other), and thus the less concentrated (more dilute) the solution becomes.
In other words, more solvent = higher volume of solution = more dilute or less concentrated solution.
(One easy way to demonstrate this is to see how bland soda tastes when you add a bunch of water to it. The taste was diluted.)