CHEMISTRY · Single correct · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
When solid NaCl dissolves in water, the lattice breaks apart into hydrated Na+ and Cl− ions. Which statement most strongly supports classifying this process as a chemical rather than a purely physical change?
(a) Because the dissolution is accompanied by an enthalpy change (ΔHsoln), the energy transfer shows that a chemical change has taken place.
(b) Hydrated Na+ and Cl− ions are chemically different species from the ions in the solid lattice, indicating that new substances are formed.
(c) Ionic bonds in the crystal lattice are broken, and the breaking of chemical bonds is a key signature of a chemical change.
(d) The resulting solution conducts electricity whereas solid NaCl does not, so the appearance of this new property proves a chemical change occurred.