OIA1011 EQUILIBRIUM OF ACID-BASE CHEMISTRY I

What are acids and bases according to Arrhenius' definition?

Acids produce H⁺ (or H₃O⁺) in water; bases produce OH⁻ in water

Define acids and bases using Bronsted-Lowry theory.

Acids are proton donors; bases are proton acceptors

What is a Lewis acid and a Lewis base?

A Lewis acid accepts an electron pair; a Lewis base donates an electron pai

What is the autoionization constant of water (Kw) at 25°C?

Kw=[H+][OH−]=1.0×10^−14.

How is pH calculated?

pH=−log⁡[H+].

What is the relationship between pH and pOH?

pH+pOH=14 at 25°C

What is the pH of a neutral solution at 25°C?

pH = 7, where [H+]=[OH−]=1.0×10^−7 M.

What characterizes strong acids and bases?

They completely ionize in water

Give an example of a weak acid and its dissociation constant (Ka

Acetic acid, Ka=1.75×10^−5.

What is the relationship between Ka, Kb, and Kw?

Ka×Kb=Kw

What is the Henderson-Hasselbalch equation for pH?

pH=pKa+log⁡([A⁻][HA]).

When does pH equal pKa?

When the concentrations of the acid and its conjugate base are equal

What is a buffer?

A solution that resists changes in pH when small amounts of acid or base are added

Give an example of a buffer system.

Acetic acid and sodium acetate

How is buffer capacity defined?

The ability of a buffer to resist changes in pH

What is the equivalence point in an acid-base titration?

The point at which the amount of acid equals the amount of base added

How does the pH change at the equivalence point of a strong acid-strong base titration?

It is approximately 7.0

What indicator is suitable for weak acid-strong base titrations?

Phenolphthalein (pH range 8.3–10.0)

Why do polyprotic acids have multiple equivalence points?

They can donate more than one proton

Why are non-aqueous titrations used?

For weak acids or bases that do not show sharp endpoints in water

Name a solvent and titrant used for weak acids in non-aqueous titrations.

Solvent: Dimethylformamide; Titrant: Tetrabutylammonium hydroxide

Name a solvent and titrant used for weak bases in non-aqueous titrations.

Solvent: Glacial acetic acid; Titrant: Perchloric acid

How is pH calculated for a 0.0001 M HCl solution?

pH = -log(0.0001) = 4.0

What is the pH of a 0.1 M sodium acetate solution?

pH=8.9 (calculated using Kb and Henderson-Hasselbalch equation)

How do acid-base indicators work?

They change color over a specific pH range depending on ionization

Give an example of an indicator for strong acid-strong base titrations.

Methyl red (pH range 4.4–6.2)

Why is phenolphthalein unsuitable for strong acid-strong base titrations?

Its color change occurs beyond the equivalence point

What is the relationship between pH and hydrogen ion concentration?

[H+]=10^−pH

How is pOH calculated?

pOH=−log⁡[OH−]

What is the effect of diluting a buffer solution?

It reduces buffer capacity but does not significantly change pH