physical change

Noun:

• physical change (a change in the physical properties of a substance, such as its shape, size, or state of matter, without a change in its chemical composition).

Adjective:

• physical (of or relating to the physical properties of a substance).

The word "physical" comes from the Greek word "physikos", which means "of nature".

The word "physical change" was first used in English in the 17th century. It was used to refer to a change in the physical properties of a substance, such as its shape, size, or state of matter.

What is a physical change? Provide an example.

Question:

Define a physical change and provide examples from everyday life. Explain how these changes differ from chemical changes and discuss the reversibility of physical changes.

Answer:

A physical change refers to a transformation in the appearance or state of matter without altering its chemical composition. Examples of physical changes are melting ice into water, breaking glass, or tearing paper. These changes involve alterations in properties like size, shape, phase, or state of matter, but the identity of the substance remains the same.

In contrast, chemical changes involve a rearrangement of atoms, leading to the formation of new substances with distinct properties. Burning wood to produce ash, rusting of iron, and cooking food are examples of chemical changes.

One key characteristic of physical changes is their reversibility. In the examples mentioned, the melted ice can be frozen back into ice, the broken glass can be reassembled, and the torn paper can be mended. This distinguishes physical changes from chemical changes, which often involve irreversible transformations.

Understanding physical changes is essential in various fields, including materials science and engineering. The ability to manipulate matter's physical properties without altering its chemical nature has practical applications in designing new materials, enhancing product performance, and even shaping our daily experiences.