Question

question 2
why did the rubbing alcohol on the instructors hand feel cold?
the alcohol cooled down and froze when it touched the air
the particles got warmer and moved slower over time
the alcohol became a solid and took heat from the hand
the alcohol particles gained heat as they turned into gas
question 3
what does the chocolate shell demo show about how solids change
cold temperatures cause particles to slide past one another

Explanation:

When rubbing alcohol is on the hand, it undergoes evaporation. Evaporation is an endothermic process. In an endothermic process, the substance (alcohol in this case) absorbs heat from the surroundings (the hand). As the alcohol particles gain heat, they have enough energy to overcome the intermolecular forces and turn into gas (vaporize). This heat absorption from the hand makes the hand feel cold.

• The first option is incorrect because rubbing alcohol has a low freezing point and does not freeze at room - temperature conditions when applied on the hand.
• The second option is wrong because when particles get warmer, they move faster (not slower) as temperature is related to the kinetic energy of particles (higher temperature means higher kinetic energy and faster movement).
• The third option is incorrect as rubbing alcohol is a liquid at room temperature and does not become a solid under these conditions while absorbing heat from the hand.

Answer:

The alcohol particles gained heat as they turned into gas.