Question: PHYSICAL CHANGE

Answer: CHEMICAL CHANGE

Question: When a substance changes from one state of matter to another (for example, changing from solid to liquid, from liquid to solid, or from liquid to gas), the composition of the substance remains the same.

Answer: When a substance changes color, the chemical composition of the substance may have changed (for example, iron turns to a reddish-brown when it rusts, apples brown when they react with oxygen in the air, or marshmallows turn black when burned).

Question: Examples of change in state might include: melting of ice cream, hardening of melted wax, or evaporating of water from wet clothes.

Answer: It is possible to have a color change without a chemical change (for example, adding food coloring to water)

Question: When a substance changes directly from a gas to a solid (the forming of frost from water vapor) or from a solid to a gas (dry ice, solid air fresheners) that change of state is called sublimation. This is still a physical change because the composition of the substance remains the same.

Answer: When a substance is combined with another substance, there may be an increase or decrease in temperature (for example, when wood burns to ash and gases, the temperature increases.

Question: When a substance changes in size or shape (for example, cutting, tearing, dissolving, stretching, or wrinkling), its composition remains the same.

Answer: NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2