Plateau — Science definition
Defined in 2 courses:
- Approximately level portion of a graph. (Physical Science: Matter, Forces & Energy)
- A section where temperature remains nearly constant while energy changes phase. (Physical Science: Chemistry)
Where it is taught
- Heating Curves & Energy During Phase Change — Phases of Matter, Physical Science: Matter, Forces & Energy, Grade 8
- Heating Curves & Phase-Change Energy — States of Matter & Gases, Physical Science: Chemistry, Grade 11
In use
A real curve may slope through an apparent plateau because of heat loss, impurities, sensor position, or incomplete thermal equilibrium.
Heating Curves & Phase-Change Energy
Questions using plateau
Problem 1
Answer and explanation
400 J enters during the four-minute interval. In the simplified model it supports melting and changed particle interactions while the temperature stays approximately constant. It is not missing energy. Some real input can also reach the container or surroundings, so attributing all 400 J to the sample requires an idealized boundary and negligible losses.
400 J enters during the four-minute interval. In the simplified model it supports melting and changed particle interactions while the temperature stays approximately constant. It is not missing energy. Some real input can also reach the container or surroundings, so attributing all 400 J to the sample requires an idealized boundary and negligible losses.
Response criteria
- Use the supplied conditions and relevant evidence.
- Explain the scientific mechanism or calculation.
- State a meaningful limitation or testable next step.
Problem 2
Hints
Distinguish the observed quantities, the proposed mechanism and its conditions.
Answer and explanation
Input is 480 J. Energy can change phase fraction and particle interactions during the plateau. In a real apparatus some energy can warm the container or leave to surroundings, so an ideal sample-only account needs stated assumptions.
Input is 480 J. Energy can change phase fraction and particle interactions during the plateau. In a real apparatus some energy can warm the container or leave to surroundings, so an ideal sample-only account needs stated assumptions.
Problem 3
Answer and explanation
No. A phase-change interpretation is supported by the growing liquid fraction, but 12 °C is not ordinary-pressure pure water’s melting point. Composition, pressure and other properties need to be checked.
Use both temperature and phase evidence.
Do not treat every plateau as water melting at a universal temperature.
No. A phase-change interpretation is supported by the growing liquid fraction, but 12 °C is not ordinary-pressure pure water’s melting point. Composition, pressure and other properties need to be checked.
Response criteria
- Use the named labels, directions or supplied quantities accurately.
- Connect the visual evidence to the scientific mechanism or calculation.
- State the relevant model conditions or limitation.
Problem 4
Answer and explanation
No. A phase-change interpretation is supported by the growing liquid fraction, but 12 °C is not ordinary-pressure pure water’s melting point. Composition, pressure and other properties need to be checked.
Use both temperature and phase evidence.
Do not treat every plateau as water melting at a universal temperature.
No. A phase-change interpretation is supported by the growing liquid fraction, but 12 °C is not ordinary-pressure pure water’s melting point. Composition, pressure and other properties need to be checked.
Response criteria
- Use the named labels, directions or supplied quantities accurately.
- Connect the visual evidence to the scientific mechanism or calculation.
- State the relevant model conditions or limitation.