when increasing pressure, why does:
- melting point decrease?
- freezing point decrease?
from solid to liquid:
is in rigid tetrahedral structure - as pressure increases, distance between molecules decrease
- hydrogen bonds get shorter (there is an optimal distance for H-bonds)
- nuclear repulsion becomes significant, weakening bonds
from liquid to solid:
- separate into 3 cases:
- molecules optimally far apart to form H-bonds
- molecules too far apart to form H-bonds
- molecules too close to form H-bonds
- increasing pressure makes far molecules closer
- increasing pressure makes molecules even closer, increasing pauli repulsion and making them bounce away/forcing them apart