Solutions:
More Vocab
Soluble
soluble: capable of being dissolved
a substance that dissolves in another
substance is said to be soluble in that
substance
Insoluble
a substance that does not
dissolve in another substance
• solubility: maximum amount substance
that dissolves in given amount of another
substance
– LIMITED amount solute that dissolves in
given amount solvent
– affected by temperature and pressure
• rate of dissolving is different from
amount that will dissolve!
• rate is how fast
• amount is how much
factors that affect the rate of
dissolving:
• temperature
• stirring or agitation
• amount of surface area of solute
• amount of solute already dissolved
Dissolving
• dissolving is physical change
source
dissolved covalent substances:
produce MOLECULES in solution
C6H12O6(s) + H2O(l) C6H12O6(aq)
dissolved ionic substances:
produce IONS in solution
NaCl(s)+H2O(l)  Na+1(aq) + Cl-1(aq)
Solvation
• interaction between solvent molecules & solute particles
– solute particles surrounded by solvent particles during
dissolving process
• solute particles may be:
• ions
• polar molecules
• non-polar molecules
• solvent molecules may be:
• polar
• non-polar
Solvation in different systems.
Hydration
describes solvent-solute interaction
when solvent is water
hydration of chloride ion
also called:
molecule-ion interaction
Molecule-ion interaction
Solute-solvent interaction
must be greater than:
interaction between
solute particles
for dissolving to occur
Solubility
• amount solute dissolved in specific
amount solvent at given TEMPERATURE
and PRESSURE
• units:
grams solute per 100 grams solvent
Solubility Curves of Selected SOLIDS
solubility traces
for most solids
have (+)’ve
slopes;
the hotter the
solvent, the
more solute
dissolves
Solubility Curves of Selected GASES
solubility
traces for all
gases have
(–)’ve slopes
Do you know why most fish prefer cold water?
Vocabulary Interlude
• miscible: two liquids that WILL MIX
together in any amounts
– water and ethanol are miscible in all
proportions
• immiscible: liquids that will NOT MIX
– oil and water are immiscible
Oil & H2O are immiscible
Types of Solutions
Matter
Mixtures
Pure Substances
Elements
Compounds
Homogeneous
Mixtures =
Solutions
Heterogeneous
Mixtures
Conduct current
Nonconductor
Electricity
• What do you need to conduct
electricity?
mobile, positively charged particles!!!!
Vocabulary Interlude
• electrolyte:
• substance that dissolves in water to form
solution that conducts electricity
• ions present in solution
• non-electrolyte:
• substance that dissolves in water to form
solution that does not conduct electricity
• neutral molecules present in solution
electrolyte vs. non-electrolyte
Which solution conducts a current?
Dilute vs. Concentrated
• concentrated
–large amounts of solute present
• dilute
–small amounts of solute present
Which solution is
most dilute?
most
concentrated?
How can you tell?
the stronger the color, the more
concentrated the solution
to dilute a solution: add MORE solvent
Which solution is
more concentrated?
More dilute?
What can you say
about the # of solute
particles in pictures
b and c?
the # is the same!
Unsaturated Solution
less than maximum amount solute
that will dissolve at given T and P
Saturated Solution
• no more solute will dissolve at given
T&P
• solubility = amount solute required to
form saturated solution
The solution is saturated when the solute
stops dissolving

Dynamic Equilibrium in Saturated Solution
microscopic level: rate dissolving = rate recrystallization
macroscopic level: no apparent change
Supersaturated Solution
• contains more solute than
saturated solution
–VERY unstable
–have to be clever to make these
(need to use heat)
Testing for saturation:
add additional crystal of solute into
solution and see what happens
3 possible results:
• crystal dissolves: unsaturated solution
• crystal sinks to bottom of solution:
saturated solution
Bam! Suddenly have
lots of solid solute
in beaker:
supersaturated solution
What kind of solution was this?
How do terms
saturated,
unsaturated &
supersaturated
fit in with the solubility curves?
saturated solns:
• any point on trace line
(max solute dissolved)
supersaturated solns:
• all points above trace
lines (more than max)
unsaturated solutions:
• all points below trace
lines (less than max)
A
B
characterize points
A, B, C, D with respect
to KNO3 trace line
(dilute, concentrated, saturated,
unsaturated, or supersaturated)
A,C = concentrated &
supersaturated
C
D
B=concentrated &
saturated
D = dilute &
unsaturated
Solubility Graphs
• traces: have positive or negative slopes
• most solids have positive slope
– the hotter the water, the more solute dissolves
– The colder the water, the less solute dissolves
• all gases have negative slope
– the hotter the water, the less gas dissolves
– The colder the water, the more gas dissolves
Summary of Dissolving
• occurs at surface of solid
• interaction: between solute & solvent
– interaction called “solvation”
– interaction called “hydration” (if solvent is H2O)
• involves: change in energy