NY Chemistry Regents Exam Jan 2023
Which process represents a chemical change? (1) Iodine sublimes. (2) Water evaporates.
(3) An ice cube melts.
(4) A candle burns in air.
Solution: A chemical change is a change where an identity of the substance changes (a reaction will happen). Phase changes are not reactions and are therefore physical changes. A candle burning represents a reaction and is therefore a chemical change.