CHEM 1R03 Lecture Notes - Lecture 20: Ionic Compound, Titration, Reagent
Chemistry Lecture Twenty
Solutions
•There are two types of mixtures, those that are heterogeneous which are non-
uniform and they contain regions with different properties than other regions
•The other type of mixture is homogeneous which is uniform throughout
•Homogeneous mixtures are pure substances and solutions are homogeneous
mixtures
•A solute is the dissolved substance, it also appears to have disappeared when it
takes on the state of the solvent
•The solvent is the substance that the solute dissolves in which does not appear to
change stage
•Remember that when both the solute and solvent have the same state, the solvent
is the component present in the highest percentage
•Solutions in which the solvent is water are called aqueous solutions
•Water is also the universal solvent
•When solute particles are surrounded by solvent molecules we say they are
solvated
•When ionic compounds dissolve in water they dissociate into ions
•The ions that become surrounded by water molecules are said to be hydrated
•Molecules that are small and have polar groups tend to be soluble in water
•The ability to H-bond with water enhances solubility
•Then one substance (solute) dissolves in another (solvent) it is said to be soluble
•Remember that salt is soluble in water and gases are always soluble in each other
•When one substance does not dissolve in another they are said to be insoluble
•Note that oil is insoluble in water
•There is usually a limit to the solubility of one substance in another
•Molecules that are similar in structure tend to form solutions
•Remember that like will dissolve like
•The solubility of the solute in the solvent depends on the temperature