Entropy

Define the system and the surroundings, whether the process is exothermic or endothermic, and the sign of ΔH(+/-) in the following scenarios:

A candle burns in a room

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• system: candle
• surroundings: room
• exothermic, (-)

An ice cube melts on the floor

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• system: ice cube
• surroundings: floor
• endothermic, (+)

A plant absorbs CO2 from the atmosphere.

system: plant
surroundings: atmosphere
endothermic, (+)

Spontaneous Process

• Spontaneous processes are those that can proceed without any outside intervention.
• Processes that are spontaneous in one direction are nonspontaneous in the reverse direction.
• Thermodynamically favorable.