L1: pH of Common Solutions

pH

pH

A measure of the acidity or basicity of a solution, expressed in units.

Acid

A substance with a pH less than 7 that forms hydrogen ions (H+) in solution and neutralizes bases.

Properties of Acid

• pH is less than 7

• neutralizes bases

• Forms H+ ions in solution

• Corrosive

  • reacts with most metals to form hydrogen gas

• Good conductors of electricity

  • bc of ions generated

• Generate ions

  ex. HNO3 + H3O → H3O+ + NO3

Base

A substance with a pH greater than 7 that usually forms hydroxide ions (OH-) in solution and neutralizes acids.

Properties of a Base

• Feels slippery

• Dissolves fats and oils

• Usually forms OH- ions in solution

• Neutralizes acids

Strong Acid

An acid that ionizes completely in solution, such as hydrochloric acid (HCl) or sulfuric acid (H2SO4).

Weak Acid

An acid that does not ionize completely in solution, such as acetic acid (HC2H3O2) or phosphoric acid (H3PO4).

Strong Base

A base that ionizes completely in solution, such as sodium hydroxide (NaOH), barium hydroxide, and calcium hydroxide.

Weak Base

A base that does not ionize completely in solution, such as ammonia (NH3) or urea (CO(NH2)2).

Indicators

Penolphthalein

Bromthymol blue

Litmus

Reaction with Phenolphthalein Indicator

Acid - Colorless

Neutral - Faint pink

Base - Dark pink

Reaction with Bromthymol blue Indicator

Acid - Yellow

Neutral - Green

Base - Blue

Reaction with Litmus Indicator

Acid - red

Neutral ----

Base - Blue

pH Scale

A scale used to measure the acidity or basicity of a solution, ranging from 0 (most acidic) to 14 (most basic).

pH Meter

A device used to measure the pH of a solution electronically.

pH Paper

Paper strips that change color to indicate a specific pH value when dipped into a solution.

Buffer

A solution that resists changes in pH when small amounts of acids or bases are added.

Arrhenius Acid

An acid that produces hydrogen ions (H+) in water.

Arrhenius Base

A base that produces hydroxide ions (OH-) in water.

Bronsted-Lowry Acid

An acid that donates a hydrogen ion (H+) in a reaction.

Bronsted-Lowry Base

A base that accepts a hydrogen

Conjugate acid

• mpound formed when a base gains a hydrogen ion

• species formed when a base has accepted proton

Conjugate base

• compound formed when an acid loses a hydrogen ion

• species formed when an acid has donated or removes a proton