1. The problem statement, all variables and given/known data Water at room temperature is placed in a flask connected by a rubber tubing to a vacuum pump, and the pump is turned on. Ater several minutes, the volume of the water has decreased and what remains has turned to ice. Explain 3. The attempt at a solution This is the answer from the solutions manual but i don't understand. "As the pressure over the liquid H2O is lowered, h2O vapor is removed by the pump. As h2o vapor is removed, more of the liquid h2o is converted to h2o vapor. this conversion is an endothermic process and the temperature decreases. the combination of both a decrease in pressure and temperature takes the system across the liquid/solid boundary in the phase diagram so the h2o that remains turns to ice." What exactly is a vacuum pump, does this just suck up all the air in the flask? are we supposed to assume that the flask is closed? The part i dont' understand is, how is the pressure over the liquid h2o lowered. where does the H2O vapor come from? I mean the water is at room temp so how come theres h2o vapor. ANd the part about "h2o vapor removed, more liquid h2o is converted to h2o vapor", how does this occur?