ConceptThermodynamics
← All conceptsInternal energy & heat
internal energy U as molecular KE+PE (state variable), heat Q as transferred energy (process quantity), phase change at constant T (latent heat raises molecular PE, KE-sum unchanged), heat flows hot→cold
12 ways this goes wrong. Each one is a named misconception the questions are built to catch.
- Absolute zero misplacedPlaces absolute zero at 0 Celsius, or claims molecules move fastest there instead of having minimum motion.→
- Boiling/evaporation confusedTreats vaporization as occurring only at the boiling point, ignoring surface evaporation below boiling and its cooling effect.→
- Cold flows into objectsDescribes 'coldness' as a substance flowing into an object, rather than heat flowing out of it.→
- Heat flows cold to hotBelieves heat spontaneously flows from a colder body to a hotter one without any external work.→
- Heat vs temperature confusedUses heat (energy transferred) and temperature interchangeably, e.g. says a hotter object necessarily contains more heat.→
- Internal energy flat during phase changeConcludes internal energy is unchanged during a constant-temperature phase change because temperature is constant, ignoring the PE rise.→
- Internal energy ignores amountEquates internal energy with temperature alone, ignoring that more particles at the same temperature hold more internal energy.→
- Internal energy is heatTreats internal energy as 'the heat stored in a body' rather than as a state variable, with heat being energy only in transit.→
- Internal energy is only KEDefines internal energy as molecular kinetic energy alone, omitting the molecular potential-energy contribution.→
- Kelvin-Celsius offset droppedConverts a single temperature between Kelvin and Celsius without the 273 offset, or wrongly applies the offset to a temperature difference.→
- Latent heat raises molecular KEClaims the latent heat absorbed during melting/boiling raises average molecular KE, when at constant T it raises molecular PE and the KE-sum is unchanged.→
- Temperature rises during phase changeAssumes temperature keeps increasing while a substance melts or boils, ignoring the constant-temperature plateau.→
