Physical and Chemical Changes Flashcards

Study Notes

Physical Change

Involves alterations in size, shape, and color without changing molecular structure.
No new substance is formed; changes are mostly reversible.

Examples of Physical Changes

Water freezing, wax melting, tearing paper, boiling water, breaking a tumbler.

Chemical Change

Occurs when substances react chemically to form a new substance with different properties.
These changes are generally irreversible.

Examples of Chemical Changes

Fuel burning, cooking food, iron rusting, reaction of iron and sulfur to form iron sulfide upon heating.

Chemical Reaction

Defined as the process where substances undergo transformation to create new substances.

Reactants

The initial substances that participate in a chemical reaction.

Products

The new substances that result from a chemical reaction.

Scientific Significance of Chemical Reactions

Essential for understanding substance properties and creating new materials.
Enabled innovations in ceramics, plastics, and medicines due to extensive research in chemical changes.

Rusting of Iron

Rust is a reddish-brown substance formed when iron is exposed to moisture and air over time.
The process involves iron reacting with water and oxygen to produce iron oxide.
Rusting is particularly problematic for ships due to constant water exposure, leading to significant monetary loss.

Prevention of Rusting

Rusting can be prevented by applying a layer of paint, oil, or grease; however, if these protective layers crack, rust formation occurs.

Galvanization

A highly effective method of rust prevention by depositing a protective layer of zinc or chromium.
Commonly applied to water pipes to enhance durability.

Description

This quiz focuses on the distinctions between physical and chemical changes. It encompasses definitions, examples, and characteristics of both types of changes. Test your understanding of how substances interact and transform under various conditions.