06_Prerequisites

We know that substances like salt and sugar dissolve in water. But what do we actually mean when we say, solutes dissolve in a solvent. When a substance is dissolved in a liquid the solute molecules are accommodated in the spaces between the solvent molecules. Let us use an analogy to see the interaction between solvent and solute molecules. We need a glass, some marbles, and dry sand. # This glass is filled with small pieces of marbles, right up to the top. # You will see that there are spaces between the marbles. # Now, add some sand to it and shake the glass slightly. You will find that sand seeps through and fills the space between the marble pieces. # # Observe that # So, we just saw what we mean when we say, that solute dissolves in liquid. The solute molecules move into the spaces between the solvent molecules.