States of Matter Lab: Heating Curve and Particle Motion
Heat or cool a sample, observe solid, liquid, and gas particle motion, and connect temperature plateaus to melting, boiling, and latent heat.
Chemistry · Grade 7
States of Matter Lab: Heating Curves, Phase Diagrams, and Particle Motion
Heat or cool a sample, watch particle spacing and speed change, then test pressure-temperature conditions on a phase diagram to explain phase stability.
Heat a solid and find the first flat part of the heating curve. Record the melting plateau.
Continue heating into the liquid region. Identify when energy raises temperature again.
Move the pressure-temperature point and identify the stable region on the phase diagram.
Compare intermolecular forces and explain why phase-change temperatures are different.
Boiling plateau at 100 C: energy separates Water particles into gas. Temperature stays fixed until vaporization is complete. Progress: 16%. Water is predicted as liquid at 100 C and 1.00 atm. Strong hydrogen bonding gives water a high boiling point for a small molecule.
Lab task
Find a temperature plateau, record it, then add more heat until the next phase appears. Compare particle motion before and after the plateau.
Observation rule
During melting and boiling, added heat changes particle arrangement instead of raising temperature, so the heating curve becomes flat.
Phase diagram rule
A phase diagram predicts the stable state from pressure and temperature. The triple point is where solid, liquid, and gas can coexist.
What to prove in this lab
- Identify solid, liquid, gas, melting, and boiling regions on a heating curve.
- Explain why temperature can stay constant during a phase change.
- Relate heat input to particle motion, spacing, and phase.