The table below lists five laboratory processes carried out at 1 atm pressure

CHEMISTRY · Multi-part · AP · Chemistry · Chemical Reactions · Chemical Reactions

Problem

The table below lists five laboratory processes carried out at 1 atm pressure.

Process	Verbal Description
I	Solid iodine gently warms and generates a purple vapor without first forming a liquid.
II	Magnesium ribbon is heated strongly in air, producing a bright white light and a white powder.
III	A sample of crystalline ammonium nitrate is added to water, causing the beaker to feel cold.
IV	Molten zinc is poured onto a polished copper plate, eventually yielding a uniform golden solid (brass).
V	Liquid ethanol left uncapped in a fume hood gradually disappears over two days.

For each process, a student must decide whether the change observed is physical, chemical, or involves aspects of both. (a) For each of the five processes (I–V), classify the change as physical, chemical, or both. Record your answer in a new table with appropriate justification. (b) Choose ONE of the processes you classified as “both.” Explain, using bonding and intermolecular considerations, why both classifications are defensible for that specific example. (c) Compare the energy changes you would expect for processes II and V on a per-mole basis. Without performing numerical calculations, argue which process is likely to involve the larger enthalpy change and indicate whether that energy is primarily associated with breaking/forming chemical bonds or modifying intermolecular forces.

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