Question

Why is the melting of ice a physical change?

Answer 1

The melting of ice is a physical change because it only alters the physical state from solid to liquid without changing the composition of water. This process is reversible, and during the phase change, the temperature of water remains constant despite heat transfer.

Step-by-step explanation:

The melting of ice is considered a physical change because it involves a change in the state of water from solid (ice) to liquid without changing the chemical composition of the substance. The molecules of water, comprised of 11.19% hydrogen and 88.81% oxygen by mass, remain the same whether the water is in its solid or liquid state. This idea is supported by the physical observation that as ice melts, it changes shape and gains the ability to flow, yet the composition of the entire substance remains constant.

Reversible physical changes, such as the melting and freezing of water, are particularly important because they illustrate the ability of a substance to change form without altering its chemical identity. Water can freely transition between its different states, which include solid, liquid, and gas, depending on the conditions of temperature and pressure it is subjected to.

LibreTexts clarifies that even when a temperature change occurs due to heat transfer, during a phase change like the melting of ice, the temperature of the substance does not change. This is because all the heat energy is used to alter the state of the water, which is another hallmark of a physical change.

Answer 2

A physical change basically involves a change in physical properties. Some examples of physical properties include: texture, shape, size, color, volume, mass, weight, etc.

The water melting has changed the shape and therefore it's physical properties, but the chemical nature of the water has not been altered.
So that's why it's a physical change, and not a chemical change.