# Using the phase diagram for H_2O, what phase is water in at 1 atm pressure and -5 C?

The phase diagram plots pressure (in $\text{mm Hg}$) against temperature. While the graph is non-linear, the normal boiling point, and the normal freezing point are clearly depicted when $P = \text{1 atm"="760 mm Hg}$. The negative slope of $\frac{\Delta P}{\Delta T}$, which illustrates that ice FLOATS, is highly unusual.