A student gently warms solid iodine in a closed beaker
CHEMISTRY · Single correct · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
A student gently warms solid iodine in a closed beaker. Purple vapor quickly appears, and upon cooling shiny iodine crystals reform on the walls of the beaker.
Which statement best classifies the processes taking place and justifies this classification?
(a) The change is chemical because the appearance of the purple vapor shows that a new substance has formed.
(b) The change is chemical because iodine molecules break apart into iodine atoms in the vapor phase.
(c) The change is physical because iodine undergoes only a phase change; it remains I2 throughout the process.
(d) The change is chemical because heat must be absorbed to break the covalent bonds in solid iodine during sublimation.