CHEM 1311 Lecture Notes - Lecture 8: Strong Electrolyte, Ionic Compound, Molar Concentration
Chapter 9: Reactions in Aqueous Solutions
Focus of this section: Types of aqueous reactions
Concentrations
General Properties of Solutions:
• Solution: a homogeneous mixture
• Solute: the component that is dissolved in solvent
-- usually in smaller amount
• Solvent: medium into which solutes are mixed
-- usually in greater amount
• concentration: describes solution composition
-- dilute: ratio of solute to solvent very small
-- concentrated: ratio is large (e.g. syrup = sugar/H2O)
-- saturated: contains as much solute as can be dissolved
-- unsaturated: can dissolve more solute
-- supersaturated: contains more solute than is actually
stable at a given temperature
= formed by cooling saturated solution from a higher
temperature (solutes typically more soluble at
higher temperatures)
= any slight disturbance (tap, dust, etc.) and solute
comes out quickly as solid
= precipitate (ppt) = solid that comes out of solution
• Electrolyte – substance that dissolves in H2O giving a
solution that conducts electricity
• Nonelectrolyte – substance whose aqueous solution does
NOT conduct electricity
• What’s the difference??
-- electrolytes form IONS in solution
-- ionic compounds (electrolytes) Dissociate into
constituent ions
H2O
NaCl(s) → Na+(aq) + Cl–(aq)
H2O
K2SO4(s) → 2 K+(aq) + SO4
2–(aq)
-- (aq) indicates that each ion surrounded (solvated,
hydrated) by the solvent (H2O)
-- many molecular compounds remain intact when
dissolving in water (nonelectrolytes)
H2O
C12H22O11(s) → C12H22O11(aq)
sucrose
= do not form ions
-- some molecular compounds Ionize when dissolving in
water (therefore electrolytes)
= Ionization: formation of ions by molecular
substance when dissolving
H2O
HCl(g) → H+(aq) + Cl–(aq) (molecular acid)
NH3(g) + H2O(l) → NH4
+(aq) + OH–(aq)
(molecular base)
• strong electrolytes: dissociate/ionize completely (~100%)
-- strong conductors of electricity
-- All water soluble ionic compounds (NaCl)-solubility later
-- All strong acids (HCl)
-- All strong bases (NaOH)
Acids: tart (sour) taste (vinegar, lemon juice)
Corrode metals Typically dangerous
Produce protons (H+) in aqueous solution
Bases: bitter taste
Soapy feel (change oils/fats in skin to soap)
Produce OH– in aqueous solution
-- strong acids:
Document Summary
General properties of solutions: solution: a homogeneous mixture, solute: the component that is dissolved in solvent. - usually in smaller amount: solvent: medium into which solutes are mixed. - usually in greater amount: concentration: describes solution composition. - dilute: ratio of solute to solvent very small. - concentrated: ratio is large (e. g. syrup = sugar/h2o) - saturated: contains as much solute as can be dissolved. - supersaturated: contains more solute than is actually stable at a given temperature. = formed by cooling saturated solution from a higher temperature (solutes typically more soluble at higher temperatures) = any slight disturbance (tap, dust, etc. ) and solute comes out quickly as solid. = precipitate (ppt) = solid that comes out of solution: electrolyte substance that dissolves in h2o giving a solution that conducts electricity, nonelectrolyte substance whose aqueous solution does. - ionic compounds (electrolytes) dissociate into constituent ions. - (aq) indicates that each ion surrounded (solvated, hydrated) by the solvent (h2o)
