A student claims that the endothermic dissolving of NH₄NO₃ in water must be a…
CHEMISTRY · Single correct · CBSE · Chemistry · Is Matter Around Us Pure? · Is Matter Around Us Pure?
Problem
A student claims that the endothermic dissolving of NH₄NO₃ in water must be a chemical change because energy is absorbed to break bonds. Which critique most effectively evaluates the student’s claim?
(a) The claim is valid; any process that absorbs or releases energy must involve new substances, so the dissolving of NH4NO3 is chemical.
(b) The claim is incorrect; the dissolving of NH4NO3 actually releases heat, not absorbs it, so the student's energy argument is backward.
(c) The claim is incomplete; although ionic bonds in the crystal are broken, no new covalent bonds within the ions form, so the change is still classified as physical.
(d) The claim overlooks that ion–dipole attractions formed with water are new chemical bonds, so the overall process should still be considered a chemical change.