Transcript Acids & BasesIonic EquationsMolarity & MolalityDissociation

Acids & Bases
Ionic Equations
Molarity & Molality
Dissociation
Jaren Mackay
Molarity & Molality
Molarity
M=
𝑛
𝑣
Molality
𝑚=
𝑛
𝑘𝑔
 M = Molarity
 m = Molality
 n = moles
 n = moles
 v = volume
 kg = weight
 Molarity is the number of moles of
a substance per liter of solution.
 Molality is the number of moles of
solute per kilogram of solvent.
 Volume has to be in Liters
 Needs to be in kg.
Dilutions
 𝑀1 𝑉1 = 𝑀2 𝑉2
 Dilutions are used to see how diluted a substance is.
Practicing Molarity and Dilutions
If you have 5 moles of oxygen in a 2
liter container, what is the Molarity?
A 3.8M solution is diluted to eight
times its original volume. What is the
molarity of the diluted solution?
Ionic Equations Vocabulary
 Electrolytes are substances that dissociate into ions when dissolved in water.
 Nonelectrolyte – may dissolve in water, but it does not dissociate into ions when
it does so.
 A strong electrolyte dissociates completely when dissolved in water.
 Weak electrolytes only dissociate partially when dissolved in water
Complete Ionic Equations
 Complete Ionic Equations better represent the actual forms of the reactants and
products in a solution. All substances that are strong electrolytes are represented
as ions.
 Spectator ions do not participate in the reactions
3Ag+(aq) + 3NO3-(aq) + PO43-(aq) -> Ag3PO4 (s)+ 3K+(aq) + 3 NO3-(aq)
Net Ionic Equations
 It only includes those that are directly involved in the reaction.
 Does not include Spectator Ions
3Ag+(aq) + 3NO3-(aq) + PO43-(aq) -> Ag3PO4 (s)+ 3K+(aq) + 3 NO3-(aq)
 3Ag+(aq) + PO43-(aq) -> Ag3PO4 (s)
Writing Net Ionic Equations
 Write a balanced molecular equation
 Dissociate all strong electrolytes
 Cross out anything that remains unchanged from the left side to the right side of
the equation.
 Write the net ionic equation with what remains.
Properties of acids
 Taste sour
 Conduct electricity
 React with metals to form hydrogen gas
 Change indicators (Blue to red)
 React with hydroxides to from water and a salt.
Properties of bases
 React with acids to form water and a salt.
 Taste bitter.
 Feel slippery
 Can be strong or weak electrolytes.
 Change indicators (red litmus turns blue).
Arrhenius Definition
 Acids produce hydrogen ions in aqueous solution
 Bases produce hydroxide ions when dissolved in water.
 Limited to aqueous solutions
 Only one kind of base (hydroxides)
 NH3 (ammonia) could not be an Arrhenius base.
Bronsted-Lowry Definitions
 Broader definition than Arrhenius
 Acid is hydrogen-ion donor; base is hydrogen-ion acceptor
 Acids and bases always come in pairs.
 HCL is an acid
 Water is a base; makes hydronium ion.
Lewis Acids and Bases
 He focused on the donation or acceptance of a pair of electrons during a reaction
 Lewis Acid – electron pair acceptor
 Lewis Base – electron pair donor
 Most general definition
More definitions
 A conjugate base is the remainder of the original acid, after it donates its
hydrogen ion
 A conjugate acid is the particle formed when the original base gains a hydrogen
ion
pH scale
 The pH scale is used to determine how strong or weak an acid or base is.
pH and pOH calculations
Practice problems
pH
[ H3O1+ ]
pOH
3.78
3.89 x 10–4 M
5.19
[ OH1– ]
ACID or BASE?