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