MINI-TEST 4 STUDY GUIDE Flashcards
What is an Arrhenius Acid?
A substance that, when dissolved in water, increases the concentration of hydrogen ions (H⁺) in the solution
What is an Arrhenius Base?
A substance that, when dissolved in water, increases the concentration of hydroxide ions (OH⁻) in the solution
What is a Bronsted-Lowry Acid?
A substance that can donate a proton (a hydrogen ion H+)
What is a Bronsted-Lowry Base?
A substance that can accept a proton (a hydrogen ion H+)
What is Lewis Acid?
A substance that can accept a pair of electrons (2e-) to form a covalent bond
(ex: METAL IONS! Ag1+, Zn2+, Al3+)
What is a Lewis Base?
A substance that can donate a pair of electrons (2e-) to form a covalent bond
(ex: LONE PAIR DONORS! NH3, H2O, OH-)
How are salts most often formed?
NEUTRALIZATION REACTIONS: (BCA Table)
Acid + Base -> Salt + H2O
(HA + OH- -> A- + Water)
The positive ion (cation) of a base and the negative ion (anion) of an acid make up a salt.
What is the definition of a salt? How else are salts formed?
A salt is an ionic compound composed of positively charged ions (cations) and negatively charged ions (anions), which are held together by ionic bonds.
Also formed by:
- Precipitation Reactions
- Acid-Metal Reactions
- Base-Metal Reactions
- Evaporation of Solutions
Will all salts change the pH of water? which ones won’t?
NO! Strong Acid + Strong Base = Neutral Salt
- Cations of strong bases do not change pH
- Anions of strong acids do not change pH
When weak acids undergo hydrolysis, what happens to the pH?
- Cations of weak bases lower the pH
BECAUSE THEY’RE CONJUGATE ACIDS!
(NH3 + H2O <-> NH4+ + OH-)
^ - Anions of weak acids raise the pH
BECAUSE THEY’RE CONJUGATE BASES!
(HCN + H2O <-> CN- + H3O+)
^
How do positively charged polyatomic cations affect the pH?
Ions such as NH4+, H3O+, and NO2+ LOWER the pH BECAUSE THEY’RE ACIDS!
How do metal ions affect the pH of a solution?
Metal ions (LEWIS ACIDS) generally make pH levels drop dramatically because they produce CONJUGATE ACIDS that increase H+ concentration through hydrolysis
How can we know if a solution is acidic or basic when only given Ka and Kb values?
If Ka (of the cation) > Kb (of the anion)
Then SOLUTION IS ACIDIC
If Ka (of the cation) > Kb (of the anion)
Then SOLUTION IS BASIC
What is a conjugate acid?
A species that is formed when a base gains a proton (H⁺), or the species that results from the addition of a proton to a base.
(HA) or (BH+) if A=Acid and B=Base
What is a conjugate base?
A species that is formed when an acid loses a proton (H⁺), or the species that results from the removal of a proton from an acid.
(A-) or (B) if A=Acid and B=Base
What is the difference between strong acids and bases and weak acids and bases?
Strong: completely dissociate in water, yielding high concentrations of either H+ (acids) or OH- (bases)
* Ka or Kb»_space; 1
Weak: partially dissociate in water, yielding lower concentrations of either H+ (acids) or OH- (bases)
* Ka or Kb «_space;1
STRONG ACIDS AND BASES ARE SUPER SOLUBLE! WEAK ONES ARE NOT
What is the Autoionization of Water?
Why is this important?
The autoionization of water refers to the spontaneous reaction where water molecules react with each other to form hydronium ions (H₃O⁺) and hydroxide ions (OH⁻) in solution.
H2O + H2O <-> H3O+ + OH-
(acid) (base) (c.acid) (c.base)
(or H2O <-> H+ + OH-)
- pH = 7 *
[H+] = [OH-]
1E-7 = 1E-7
What is kW equal to?
kW = [H+]*[OH-]
kW = 1E-7 * 1E-7
kW = 1E-14
When must we account for the autoionization of water in an equilibrium reaction?
When pH is between 6 and 8 (when the initial concentration of either H+ or OH- are close to 1E-7)
How can we account for the autoionization of water in an equilibrium reaction
We must add 1E-7
What is pH? What is it equal to?
“potential” of Hydrogen ions: the measure of acidity of a solution
pH = -log[H+]
pH = 14 - pOH
What is pOH? What is it equal to?
“potential” of Hydroxide ions: the measure of basicity of a solution
pOH = -log[OH-]
pOH = 14 - pH
If pH = 4, then what does [H+] equal?
[H+] = 10^-4
(because pH = log[H+])
If pOH = 10, then what does [OH-] equal?
[OH-] = 10^-10
(because pOH = log[OH-])
What are the formulas for all 6 strong acids?
“I love to watch CSI on NBC”
HCl HNO3
H2SO4 HBr
HI HClO4
What are the names for all 6 strong acids?
“I love to watch CSI on NBC”
HCl: Hydrochloric Acid
H2SO4: Sulfuric Acid
HI: Hydroiodic Acid
HNO3: Nitric Acid
HBr: Hydrobromic Acid
HClO4: Perchloric Acid
What are the formulas and names for the 8 most common strong bases?
LiOH: Lithium Hydroxide
NaOH: Sodium Hydroxide
KOH: Potassium Hydroxide
RbOH: Rubidium Hydroxide
CsOH: Cesium Hydroxide
Ca(OH)2: Calcium Hydroxide
Sr(OH)2: Strontium Hydroxide
Ba(OH2): Barium Hydroxide
What happens to the conjugate base strength as acid strength increases?
As acid strength increases, conjugate base strength decreases.
What happens to the conjugate acid strength as base strength increases?
As base strength increases, conjugate acid strength decreases.
What is % Ionization?
What are Polyprotic Acids? What do we have to keep in mind when dealing with them?
What is pKa? What does a really negative pKa tell us?
What is pKb? What does a really negative pKb tell us?
What are the steps for setting up equilibrium reactions with weak acids and bases?
STEP 1: Write out what each substance dissolves into
STEP 2: Determine which ion(s) react with water
STEP 3: Write out equilibrium equation, excluding spectator ions
- With salts you must consider dissociation of ions!
(1. Ca(ClO)2 -> Ca2+ + 2ClO-)
(2. ClO- + H2O <-> HClO + OH-)
What makes a buffer?
What is the relationship between pH and pKa in the context of indicators?
What makes a substance soluble?
What makes a buffer?
A mixture of a weak base (or weak acid) with its conjugate acid (or conjugate base) in solution.
When can we use the Henderson Hasselbalch equation
