Brønsted-Lowry Acids, Bases, and pH Titrations

Comprehensive vocabulary flashcards focusing on acid-base chemistry, including strong/weak acids and bases, Brønsted-Lowry theory, pH calculations, and titration concepts.

Acid (General)

A substance that neutralises a base forming a salt and water, or a substance that releases hydrogen ions ($H^+$) when dissolved in water.

Base (General)

A compound that neutralises an acid forming a salt and water, accepts hydrogen ions, or contains oxide or hydroxide ($OH^-$) ions.

Alkali

A base that is soluble in water.

Brønsted-Lowry Acid

A species that gives away a proton ($H^+$).

Brønsted-Lowry Base

A species that accepts a proton ($H^+$) using its lone pair of electrons.

Amphoteric

Species that can act as both acids and bases, such as water ($H_2O$).

Proton

A name for a $H^+$ ion, as a hydrogen atom loses its only electron to leave only a proton remaining.

Strong Acid

An acid that dissociates almost completely in aqueous solutions, such as $HCl$, $HNO_3$, and $H_2SO_4$, resulting in a high concentration of $H^+/H_3O^+$ ions.

Weak Acid

An acid that partially or incompletely dissociates in aqueous solutions, such as ethanoic acid ($CH_3COOH$), $HCN$, $H_2S$, and $H_2CO_3$, establishing an equilibrium.

pH Formula

$pH = -\text{log}([H^+(aq)])$, where $[H^+(aq)]$ is the concentration of $H^+/H_3O^+$ ions.

Acid Dissociation Constant ($K_a$)

A constant used to find the concentration of $H^+$ ions in a weak acid where the concentration of ions is not equal to the concentration of the acid.

Strong Base

A base that dissociates almost completely in aqueous solutions, such as Group 1 metal hydroxides like sodium hydroxide ($NaOH$).

Weak Base

A base that partially or incompletely dissociates in aqueous solutions, such as ammonia ($NH_3$), amines, and some transition metal hydroxides.

Ionic Product of Water ($K_w$)

$K_w = [H^+][OH^-] = 10^{-14}\text{ mol}^2\text{ dm}^{-6}$ at $298\text{ K}$. (Transcript uses $mol^2\text{ dm}^{-3}$ at 298K).

Neutralisation Reaction

A reaction in which an acid ($pH < 7$) and a base or alkali ($pH > 7$) react together to form water ($pH = 7$) and a salt.

Spectator Ions

Ions not involved in the formation of water during a neutralisation reaction that instead form the salt.

Titration

A technique used in neutralisation reactions to determine the concentration of an unknown solution (analyte) by adding a titrant of known concentration.

Threshold of pH Scale

The numerical scale ranges from 1-14; acids are below 7, alkalis are above 7, and 7 is neutral.

Endpoint

The point in a titration at which an indicator changes colour.

Equivalence Point

The point halfway through the vertical region of a pH titration curve where the number of moles of alkali equals the number of moles of acid and neutralisation takes place.

Point of Inflexion

The point on the pH titration curve for a weak acid + weak alkali titration where the equivalence point occurs, as there is no vertical region.

Indicators

Substances that change colour over a specific pH range when added to acidic or alkaline solutions.

Methyl Orange

An indicator that changes colour over a pH range of $3.1-4.4$.

Phenolphthalein

An indicator that changes colour over a pH range of $8.3-10$.