How does the melting point of water change as pressure increases...?

1) As the pressure increases, the melting point of water will go up in temperature because the density of solid is less than that of liquid water.

2) The equilibrium between sublimation and deposition of a substance

3) The equilibrium between vaporization and condensation of a substance

4) If at sea-level this will be 1 atm. In other words, the vapor pressure of water at its boiling point will equal the pressure of the atmosphere.

1. For most substances, increasing the pressure when a system is in equilibrium between liquid and solid phases will increase the phase transition temperature. Water is one of a few special substances for which the pressure lowers the temperature of transition. The basic reason is that water actually expands when it goes from the liquid to solid phase.

For 2. and 3. http://en.wikipedia.org/wiki/Phase_transition

4. At the normal boiling point of 100°C, it equals the standard atmospheric pressure of 760 Torr or 101.325 kPa.

1) Depending on what you mean by melting, yes. Under extreme pressures H2O has a semi-liquid habit at temperatures below freezing.

2) Sublimation. I usually see this with dry ice.

3) vaporization/condensation, depending on which way it's going.

4) I've forgotten, sorry.

As pressure increases, the melting point of water decreases. this is because ice expands so more pressure makes it lean toward less volume in the liquid state

2 the sublimation point

3 the boiling point

4 1 atm

problem is water doesnt melt, lololol