Review from Monday 5/5
Molarity
Molality

(M)
 (m)

Describes the amount of solute
in moles and the volume of the
solution in liters.
 The amount of substance of
solute, divided by the mass
of solvent.

The number of moles of solute
per volume of solution in Liters
 The number of moles of
solute divided by the number
of kilograms of solvent

Moles of Solute = mol
Liters of Solution
L
 Moles of solute = mol
Kg of Solution
kg
Types of solutions

Solution-a homogeneous mixture

Solvent-the largest substance that is present within the solution

Solutes-the smallest substance within the solution

Aqueous solution-solutions with water as a solvent

Saturated-a solution that contains as much solute as will dissolve at the temperature

Unsaturated- a solution that has not reached the limit of solute that will dissolve

Concentrated-a large amount of solute dissolved

Dilute-a relatively small amount of solute is dissolved

Supersaturated- a solution that contains more dissolved material than could be dissolved by the solvent under normal
circumstances
Acids
Bases
 Produce hydrogen ions
 Produce hydroxide ions
 H+ or HA
 OH- or A-
 Taste sour
 Taste Bitter
 pH less than 7
 pH greater than 7
Brønsted-Lowery Model
 Acid is a proton (H+) donor, and a base is a proton acceptor
 The new acid that is formed is the conjugate acid and the
new base is the conjugate base
i.e.
HA(aq) + H2O(l)  H3O+(aq) + A-(aq)
Acid
base
conjugate acid
conjugate base
Arrhenius Acids and Bases
 Acids-dissociate in water to produce hydrogen
ions[H+]
 Bases-dissociate in water to produce hydronium ions
[H3O+]
Strong Acids
 Forward reaction predominates
 A- is a much weaker base than H2O
 When there is a strong acid, we say that HA has completely
ionized or dissociated.
i.e.
HA(aq) + H2O(l)  H3O+(aq) + A-(aq)
*HA is the strong acid
Common strong acids include: HCl, HNO3,HClO4 and H2SO4
Weak Acids
 Reverse reaction predominates
 A- is much stronger base than H2O
I.E.
HA(aq) + H2O(l)  H3O+(aq) + A-(aq)
Now A- has a much more attraction to H+ molecules than the
H2O
Diprotic Acids
 An acid that has two protons
 Example: H2SO4
pH Scale
 Acids- 0.1-6.99
 Bases-7.01-14
 Neutral 7---H2O
Calculating pH and pOH
pH
pOH
 Need to know Molarity.
Then calculate using the
expression:
pH=-log[H3O+]
 Need to know Molarity.
Then calculate using the
expression:
pOH=-log[H3O+]
 Using the hydronium ion to
calculate pH use the
expression:
10-pH
 Using the hydronium ion to
calculate pOH use the
expression:
10-pOH
The relationship between
pH and pOH
 pH + pOH = 14
 For example:
 A solution has a pOH of 11.76. What is the pH of this
solution?
 14- pOH = pH
 14-11.76= 2.24
Examples
 Find the pH of a 0.0025M HCl solution. The HCl is a
strong acid and is a 100% ionized in the H2O. The
hydronium ion is 0.0025M.
 pH=-log(0.0025M)=-(2.60)=2.60
Example
 What is the hydronium ion concentration in a solution
that has a pOH of 5.70?
 [OH-]=10-5.70 =2.00 x 10-6M
Neutralization reactions
 In chemical reaction an acid and base react to form a
salt.
 They are often exothermic reactions
 pH is not necessarily 7, could/can vary based on the
strengths of the acids and bases
 Example:
 HCl + NaOH  NaCl + H2O
Amphoteric substances
 Substances that behave as both acids and bases
 Examples: ZnO
 Acid: ZnO + 2H+  Zn2+ + H2O
 Base: ZnO + H2O + 2OH-  [Zn(OH)4]2-
Equilibrium
 Equilibrium-is the exact balancing of the two
processes, one of which is the opposite of the other.
 Equilibrium rate occurs when the rate of evaporation
exactly equals the rate of condensation
Reaction rates
 Activation energy (Ea)- is the minimum energy needed
for a reaction to occur
 Catalyst- a substance that speeds up the reaction
without being consuming.
Le Châletier’s principle
The effect of a change in concentration:
 When a reactant or product is added to a system at equilibrium, the
system shifts away from the added component. On the otherhand, if
a reactant or product is removed, the system shifts toward the
component.
The effect of a change in temperature:
 Treat energy as a reactant (endothermic) or as a product
(exothermic) and predict the direction of the shift as you would for
concentration.
The effect of a change in volume:
 The system shifts in the direction that gives the smaller number of
gas molecules
 Adding a catalyst has no effect on the position of the equilibrium