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CHEM 106 > MINI-TEST 4 STUDY GUIDE > Flashcards

MINI-TEST 4 STUDY GUIDE Flashcards

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1
Q

What is an Arrhenius Acid?

A

A substance that, when dissolved in water, increases the concentration of hydrogen ions (H⁺) in the solution

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2
Q

What is an Arrhenius Base?

A

A substance that, when dissolved in water, increases the concentration of hydroxide ions (OH⁻) in the solution

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3
Q

What is a Bronsted-Lowry Acid?

A

A substance that can donate a proton (a hydrogen ion H+)

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4
Q

What is a Bronsted-Lowry Base?

A

A substance that can accept a proton (a hydrogen ion H+)

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5
Q

What is Lewis Acid?

A

A substance that can accept a pair of electrons (2e-) to form a covalent bond
(ex: METAL IONS! Ag1+, Zn2+, Al3+)

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6
Q

What is a Lewis Base?

A

A substance that can donate a pair of electrons (2e-) to form a covalent bond
(ex: LONE PAIR DONORS! NH3, H2O, OH-)

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7
Q

How are salts most often formed?

A

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.

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8
Q

What is the definition of a salt? How else are salts formed?

A

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

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9
Q

Will all salts change the pH of water? which ones won’t?

A

NO! Strong Acid + Strong Base = Neutral Salt
- Cations of strong bases do not change pH
- Anions of strong acids do not change pH

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10
Q

When weak acids undergo hydrolysis, what happens to the pH?

A
  • 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+)
    ^
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11
Q

How do positively charged polyatomic cations affect the pH?

A

Ions such as NH4+, H3O+, and NO2+ LOWER the pH BECAUSE THEY’RE ACIDS!

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12
Q

How do metal ions affect the pH of a solution?

A

Metal ions (LEWIS ACIDS) generally make pH levels drop dramatically because they produce CONJUGATE ACIDS that increase H+ concentration through hydrolysis

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13
Q

How can we know if a solution is acidic or basic when only given Ka and Kb values?

A

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

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14
Q

What is a conjugate acid?

A

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

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15
Q

What is a conjugate base?

A

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

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16
Q

What is the difference between strong acids and bases and weak acids and bases?

A

Strong: completely dissociate in water, yielding high concentrations of either H+ (acids) or OH- (bases)
* Ka or Kb&raquo_space; 1

Weak: partially dissociate in water, yielding lower concentrations of either H+ (acids) or OH- (bases)
* Ka or Kb &laquo_space;1

STRONG ACIDS AND BASES ARE SUPER SOLUBLE! WEAK ONES ARE NOT

17
Q

What is the Autoionization of Water?
Why is this important?

A

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
18
Q

What is kW equal to?

A

kW = [H+]*[OH-]
kW = 1E-7 * 1E-7
kW = 1E-14

19
Q

When must we account for the autoionization of water in an equilibrium reaction?

A

When pH is between 6 and 8 (when the initial concentration of either H+ or OH- are close to 1E-7)

20
Q

How can we account for the autoionization of water in an equilibrium reaction

A

We must add 1E-7

21
Q

What is pH? What is it equal to?

A

“potential” of Hydrogen ions: the measure of acidity of a solution

pH = -log[H+]
pH = 14 - pOH

22
Q

What is pOH? What is it equal to?

A

“potential” of Hydroxide ions: the measure of basicity of a solution

pOH = -log[OH-]
pOH = 14 - pH

23
Q

If pH = 4, then what does [H+] equal?

A

[H+] = 10^-4
(because pH = log[H+])

24
Q

If pOH = 10, then what does [OH-] equal?

A

[OH-] = 10^-10
(because pOH = log[OH-])

25
Q

What are the formulas for all 6 strong acids?

A

“I love to watch CSI on NBC”

HCl HNO3
H2SO4 HBr
HI HClO4

26
Q

What are the names for all 6 strong acids?

A

“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

27
Q

What are the formulas and names for the 8 most common strong bases?

A

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

28
Q

What happens to the conjugate base strength as acid strength increases?

A

As acid strength increases, conjugate base strength decreases.

29
Q

What happens to the conjugate acid strength as base strength increases?

A

As base strength increases, conjugate acid strength decreases.

30
Q

What is % Ionization?

A
31
Q

What are Polyprotic Acids? What do we have to keep in mind when dealing with them?

A
32
Q

What is pKa? What does a really negative pKa tell us?

A
33
Q

What is pKb? What does a really negative pKb tell us?

A
34
Q

What are the steps for setting up equilibrium reactions with weak acids and bases?

A

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-)
35
Q

What makes a buffer?

A
36
Q

What is the relationship between pH and pKa in the context of indicators?

A
37
Q

What makes a substance soluble?

A
38
Q

What makes a buffer?

A

A mixture of a weak base (or weak acid) with its conjugate acid (or conjugate base) in solution.

39
Q

When can we use the Henderson Hasselbalch equation

A

CHEM 106 (21 decks)

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