Introduction to Acids, Alkalis, and the pH Scale

A set of vocabulary flashcards covering the definitions, formulas, and properties of acids, alkalis, neutral substances, and the pH scale based on the provided chemistry notes.

Acids

Solutions of pure compounds in water that turn litmus red and must be handled carefully due to being corrosive.

Corrosive

The ability of a substance, like concentrated acid, to eat away metals, skin, and cloth.

Weak acids

Acids that are not very corrosive even when concentrated, such as ethanoic acid, and typically have a pH between $3$ and $6.9$.

Litmus

A purple dye used as an indicator; it turns red in the presence of an acid and blue in the presence of an alkali.

Hydrochloric acid

A common laboratory acid with the formula $HCl(aq)$.

Sulphuric acid

A common laboratory acid with the formula $H_2SO_4(aq)$.

Nitric acid

A common laboratory acid with the formula $HNO_3(aq)$.

Ethanoic acid

A weak acid with the formula $CH_3COOH(aq)$ found in vinegar.

Citric acid

An acid naturally found in lemon juice.

Methanoic acid

An acid found in ant and nettle stings.

Tannic acid

An acid commonly found in tea.

Alkalis

Chemicals that turn litmus solution blue and red litmus paper blue, and can burn skin; they are often used as aqueous solutions.

Sodium hydroxide

A common laboratory alkali with the formula $NaOH(aq)$.

Potassium hydroxide

A common laboratory alkali with the formula $KOH(aq)$.

Calcium hydroxide

A common laboratory alkali with the formula $Ca(OH)_2(aq)$.

Ammonia

A laboratory alkali with the formula $NH_3(aq)$, often used in solution.

Neutral substances

Substances that do not affect the colour of litmus and have a pH of exactly $7$, such as sugar solutions or sodium chloride.

pH scale

A scale of numbers from $0$ to $14$ used to indicate the strength of an acid or an alkali.

Acidic solution

A solution that has a pH number less than $7$.

Alkaline solution

A solution that has a pH number greater than $7$.

Universal indicator

A mixture of dyes that changes to different colours at different pH values to show the strength of a solution.

Strong acids

Acids that have a low pH value, typically ranging from $0$ to $2.5$.

Strong alkalis

Alkalis that have a high pH value, typically ranging from $10.1$ to $14$.