Acids and Bases Flashcards
(Acids and Bases) Brônsted-Lowery Reactions
HA + B ⇌ BH⁺ + A⁻
HA : Acid
B : Base
BH⁺ : Conjugate acid of B
A⁻: Conjugate base of HA
(Acids and Bases) Acids ______ protons and bases ______ protons.
donate, accept
(Acids and Bases) Strong acids completely dissociate in water. Equilibrium lies…
far to the right, and thus when writing a chemical equation, use a one way arrow (→).
(Acids and Bases) Weak acids partially dissociate in water. Equilibrium lies…
to the left or roughly in the middle, and thus when writing a chemical equation, use a two way arrow (⇌).
(Acids and Bases) The “Big Six” Strong Acids
HClO₄ (perchloric acid)
HCl (hydrochloride acid)
HI (hydroiodic acid)
HNO₃ (nitric acid)
HBr (hydrobromic acid)
H₂SO₄ (sulfuric acid)
(Acids and Bases) Strong Bases
Soluble compounds containing the hydroxide ion.
Possible cations:
• All group 1A cations (K⁺, Na⁺, Li⁺, etc.)
• Ca²⁺, Sr²⁺, Ba²⁺
(Acids and Bases) Strong acids always have _________ conjugate bases.
very weak
(Acids and Bases) Very weak acids have ___________ conjugate bases.
very strong
(Acids and Bases) The stronger base always accepts the ____ protons in an acid/base reaction.
most
(Trends) Binary Acid Strengths; acid strength increases—base strength of conjugate base decreases as…
anion radius increases.
(Acids and Bases) Oxoacid Types
HOY:
H-O-Y
HYOₓ:
H-O-Y-O
|
O
(Trends) HOY Oxoacid Strengths; acid strength and Kₐ increase as…
electronegativity of Y increases.
(Trends) HYOₓ Oxoacid Strengths; acid strength and Kₐ increase as…
oxygens are added to Y.
(Acids and Bases) Carboxylic Acids
Weak organic acids that take on the form:
R-C-O-H
||
O
R—pretty much anything.
(Trends) Carboxylic Acid Strengths; acid strength increases as…
electronegativity of the elements that make up “R” increases.
(Acids and Bases) K Value of Water
Kw = 1.0*10^-14
(Acids and Bases) [H₃O⁺] > [OH⁻];
Solution is acidic.
(Acids and Bases) [H₃O⁺] < [OH⁻];
Solution is basic.
(Acids and Bases) [H₃O⁺] = [OH⁻];
Solution is neutral.
(Acids and Bases) The pH Formula(s)
[H⁺]=10^(-pH)
Thus:
pH=-log[H⁺]
or
pH=-log[H₃O⁺]
(Acids and Bases) The pH Scale
Basic
14 13 12 11 10 9 8 7 6 5 4 3 2 1
Acidic
(Problem Solving) When calculating pH for strong acids, we assume 100% dissociation.
Example: Find the pH of a 2.5 M HCl solution.
pH=-log[H⁺]
pH=-log[2.5]
pH=-0.40
Number of significant figures in the concentration is equal to the number of decimal places given to the pH.
(Acids and Bases) The pOH Formula
pOH=-log[OH⁻]
(Acids and Bases) The stronger the acid, the ______ the Kₐ value.
larger
(Acids and Bases) The stronger the base, the ______ the Kb value
larger
(Acids and Bases) pK Equations
pKa=-log(Ka)
Ka=10^(-pKa)
pKb=-log(Kb)
Kb=10^(-pKb)
(Trends) The stronger the acid, the _______ the pKa.
smaller
(Trends) The stronger the base, the _______ the pKb.
smaller
(Acids and Bases) Kw Equations
Kw=[H₃O⁺][OH⁻]
Kw=Ka*Kb
-logKw=-logKa*-logKb
pKw=pKa+pKb=14
pKw=pOH+pH=14
(Acids and Bases) pKa > pKb
The solution is acidic.
(Acids and Bases) pKa < pKb
The solution is basic.
(Acids and Bases) pKa = pKb
The solution is neutral.
