Which hazard may occur in a closed vessel when the reaction temperature reaches a level above the mixture's boiling point?

Which hazard may occur in a closed vessel when the reaction temperature reaches a level above the mixture's boiling point?

• A. Pressure buildup in a closed vessel
• B. Color change
• C. No hazard
• D. Solvent deposition

Answer: (A)

When a liquid is heated above its boiling point in a closed vessel, it boils and forms vapor. Because the vessel is sealed, this vapor has nowhere to escape, so the internal gas pressure rises. That rise in pressure is the hazard: overpressure can cause the container to vent, rupture, or fail violently. This is why pressure buildup in a closed vessel is the most plausible hazard in this scenario. Color change isn’t inherently hazardous in this context, and deposition of solvent would require cooling and condensation elsewhere, not the elevated temperature situation described.

When a liquid is heated above its boiling point in a closed vessel, it boils and forms vapor. Because the vessel is sealed, this vapor has nowhere to escape, so the internal gas pressure rises. That rise in pressure is the hazard: overpressure can cause the container to vent, rupture, or fail violently. This is why pressure buildup in a closed vessel is the most plausible hazard in this scenario.

Color change isn’t inherently hazardous in this context, and deposition of solvent would require cooling and condensation elsewhere, not the elevated temperature situation described.