Determine whether the process of dry ice evaporating is endothermic or exothermic and indicate the sign of ΔH.
A
The process is exothermic and ΔH is negative.
B
The process is endothermic and ΔH is positive.
C
The process is endothermic and ΔH is negative.
D
The process is exothermic and ΔH is positive.
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1
Understand the concept of endothermic and exothermic processes: Endothermic processes absorb heat from the surroundings, while exothermic processes release heat.
Identify the process: Dry ice (solid CO2) evaporating involves the transition from solid to gas, which is sublimation.
Recognize that sublimation requires energy: For a substance to change from solid to gas, it must absorb energy to overcome intermolecular forces, indicating an endothermic process.
Determine the sign of ΔH: In endothermic processes, the system absorbs heat, resulting in a positive change in enthalpy (ΔH > 0).
Conclude that the evaporation of dry ice is endothermic with a positive ΔH, as energy is absorbed during sublimation.