Physical and Chemical Changes — Flashcards

Answer

A physical change is a change in which no new substance is formed. Only physical properties such as state, shape, size, or appearance change. The chemical composition remains the same.

Answer

A chemical change is a permanent change in which a new substance with different properties is formed. The original substance cannot be obtained back by simple physical methods.

Answer

Ice and water have the same chemical composition, H2O. During melting, only the state changes from solid to liquid. No new substance is formed, so it is a physical change.

Answer

Water changes from liquid to solid, but its chemical composition remains H2O. This is a reversible physical change. Equation: Water xrightarrow{freezing} Ice melting [Water, Ice - reversible physical …

Answer

Camphor changes from solid to vapour and then back to solid without forming a new substance. The change is temporary and reversible, so it is a physical change.

Answer

A reversible change is a change that can be reversed by changing the conditions. Water freezing into ice and ice melting into water are reversible changes.

Answer

An irreversible change cannot be brought back to the original state. Burning a piece of paper into ash is an irreversible change.

Answer

Burning paper forms a new substance, ash. Ash cannot be changed back into paper by simple physical methods, so the change is chemical and irreversible.