Concept:The severity of thermal burns relies on the total amount of heat energy transferred to the skin.
Formula:$$ Q_{\text{total}} = Q_{\text{condensation}} + Q_{\text{cooling}} $$
Solution:- When boiling water at \( 100^\circ\text{C} \) touches the skin, it releases heat as it cools down to body temperature.
- When steam at \( 100^\circ\text{C} \) touches the skin, it must first undergo a phase change (condense) into liquid water before it can cool down.
- This phase change releases a massive amount of hidden energy known as the latent heat of vaporization (\( 40.6 \text{ kJ/mol} \)). This extra, intense heat transfer causes significantly more severe burns.
Why other options are incorrect:Freely moving molecules do not intrinsically cause burns; heat transfer does. Steam still technically contains some transient H-bonding, though vastly reduced, but this doesn't explain the thermodynamic energy release.
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