The Two Flat Spots

Put a burner under a block of ice and the thermometer climbs — then stops dead, twice, while the burner keeps burning. Those flat stretches are where the heat is going into pulling molecules apart instead of speeding them up. And the second flat stretch is nearly seven times longer than the first. That length is not an accident, and it is the whole topic.

8 STEPS · 6 QUICK CHECKS · 1.00 mol H₂O · ΔH_fus = 6.01 kJ/mol · ΔH_vap = 40.7 kJ/mol · v2