Unit 11: Acid and Bases
For a complex ion: the total charge of the ion is the _______ of all the charges of the ions in the complex.
sum
An anion that is the conjugate base of a weak acid is a...
weak base
The smaller the value of Kb, the ________ the base.
weaker
The stronger the H─X bond, the _______ the acid.
weaker
Substances that can act as acids or bases
amphoteric
Determine if it acts as a acid, base, or neutral C₇H₅O₂⁻ I⁻ NO₃⁻
basic neutral neutral
Anions form either _____ or __________ solutions
basic or neutral
[H₃O⁺] < [OH⁻]
basic; pH > 7
Any base to which a proton has been added
conjugate acid
any acid from which a proton has been removed
conjugate base
Down a group, acidity increases due to
decreasing bond strength
Three factos that the strength of the bond in oxyacids depend on:
electronegativity of the central atom number of O atoms bonded to the central atom number of O per H
Across a period, acidity increases due to
increasing electronegativity H-X bond is more polarized and weaker H-X bond is easier to break releasing H⁺
The ______ the bond length, the more easily the bond is broken releasing the H⁺ and the stronger the acid
longer
Determine if it acts as a acid, base, or neutral Sr²⁺ Mn³⁺ C₅H₅NH⁺
neutral acid acid
Determine if it acts as a acid, base, or neutral Br⁻ ClO⁻ CN⁻ Cl⁻
neutral basic basic neutral
The greater the number of O atoms bonded to the central atom, the more polarized the O-H bond, and the _______ the acid
stronger
[H₃O⁺] > [OH⁻]
acidic; pH < 7
More O atoms per H = _________ acid
stronger
Write equation and determine acid, basic, neutral: solid barium oxide is added to water
BaO(s) + H₂O(l) → Ba(OH)₂(aq)
Pick the stronger oxyacid: CCl₃COOH and CH₃COOH
CCl₃COOH (Cl is more EN than H)
Arrange in order of increasing basicity CH₃NH₃Br, KOH, KBr, KCN
CH₃NH₃Br < KBr < KCN < KOH
Which is the stronger base? CN⁻ (Ka=4.9 x 10⁻¹⁰) or ClO⁻ (Ka=2.9 x 10⁻⁸)
CN⁻
Which is the stronger base? F⁻ (Ka=3.5 x 10⁻⁴) or ClO⁻ (Ka=2.9 x 10⁻⁸)
ClO⁻
Write the formula for the conjugate base of each acid: HCl H₂SO₃ HCHO₂ HF
Cl⁻ HSO₃⁻ CHO₂⁻ F⁻
Number of electron pairs that a metal will accept.
Coordination number
Write an equation that show how the weak base C₆H₅NH₂ ionizes water to from OH⁻.
C₆H₅NH₂(aq) + H₂O(l) → C₆H₅NH₃⁺(aq) + OH⁻(aq)
Which is the stronger base? F⁻ or Cl⁻
F⁻ (Conj. base of weak acid is a strong base)
Name the six STRONG acids
HCl HBr HI HNO₃ H₂SO₄ HClO₄
Pick the stronger acid: HF and HCl
HCl (lower bond strength because Cl⁻ is larger than F⁻ so the H-Cl bond length is greater than the H-F bond length)
Pick the stronger oxyacid: HClO and HBrO
HClO; Cl is more EN than Br
Pick the stronger oxyacid: HClO₂ and HClO
HClO₂ (has two O atoms to polarize the O-H bond and weaken it)
Name the five WEAK acids
HF HC₂H₃O₂ H₂SO₃ H₂CO₃ H₃PO₄
Pick the stronger acid: H₂O and HF
HF (F is more EN than O so HF bond is more polarized than HO bond)
Arrange by increasing acid strength HClO₃, HIO₃, HBrO₃
HIO₃ < HBrO₃ < HClO₃ increasing EN
Which is the stronger base? Cl⁻ or H₂O
H₂O
Pick the stronger oxyacid: H₂SO₄ and H₂SO₃
H₂SO₄ (Two more O atoms that are not bonded to a H. These two O atoms can polarize and weaken the O-H bonds and make it easier to release the H⁺ ions)
Pick the stronger acid: H₂Se and H₂S
H₂Se (lower bond strength than H₂S becuase the Se²⁻ ion is bigger than S²⁻ ion so the H-Se bond length is great than the H-S bond length)
Rank the three Ka from largest to smallest
Ka1 > Ka2 > Ka3
[A²⁻] = ________ as long as the second ionization is negligible.
Ka2
Which is the stronger base? NO₂⁻ or NO₃⁻
NO₂⁻ (Conj. base of weak acid is a strong base)
Arrange by increasing acid strength H₂Te, HI, H₂S, NaBr
NaBr < H₂S < H₂Te < HI NaBr is neutral H₂Te has a longer bond length, making it stronger than H₂S HI strongest because most polarized with long bonds
Arrange in order of increasing acidity NaCl, NH₄Cl, NaHCO₃, NaOH
NaOH < NaHCO₃ < NaCl < NH₄Cl
Write equation and determine acid, basic, neutral: Dinitrogen pentoxide gas is bubbled through water
N₂O₅(g) + H₂O(l) → 2 HNO₃(aq) ACIDIC
Strength of an oxyacid depends on strength of _____ bonds.
O-H
Contain H, O and another element (central atom) O atoms are bonded to the central atom
Oxyacids
In a mixture of weak acids, to find the pH, there are three sources of H₃O⁺. Which do you use to calculate the pH?
The substance with a higher Ka value
Determine if it acts as a acid, base, or neutral NH₄⁺ Na⁺ Co³⁺ CH₂NH₃⁺
acidic neutral acidic acidic
A cation that is a small, highly charged metal ( > 2+) is..
Weak acid
A cation that is the conjugate acid of a weak base is...
Weak acid
Cations form either _____ or __________ solutions
acidic or neutral
Determine if it acts as a acid, base, or neutral FeCl₃ NaF CaBr₂ NH₄Br C₆H₅NH₃NO₂
acidic basic neutral acidic Need more info (acidic/basic) compare Ka of C₆H₅NH₃⁺ with Kb of NO₂⁻
A cation that is the counter-ion of a strong base is... (Group 1A and 2A)
pH neutral
An anion that is the conjugate base of a strong acid is...
pH neutral
In a mixture of a strong and weak acid, how do you find the pH?
pH of the strong acid
The more ______ the bond, the more easily the bond is broken releasing the H⁺ and the stronger the acid.
polarized
Contain two or more ionizable protons.
polyprotic acid
Brønsted-Lowry bases are _________.
proton acceptors
Brønsted-Lowry acids are _________.
proton donors
Generally, the difference in Ka values is great enough so that the ________ ionization does not happen to a large enough extent to affect the pH. Most pH problems just do first ionization. Except H₂SO₄
second
Ka2 is ________ than Ka1 because H⁺ separates from a neutral molecules while the second one separated from an anion
smaller
Higher EN of the central atom of an oxyacid = ________ acid
stronger