Here we're told that a substance has a triple point of -45�C and 500mm of mercury. What is the most likely phase change to occur for a solid sample of this substance as it's heated from -60�C to 10�C at a pressure of 490mm of mercury? All right. So first of all, they tell us our triple point. And on this phase diagram, our triple point would be here, the point in which all three phases meet together.
Now if we take a look, we're told that it happens at 500 meters, millimeters of mercury and at -45�. Now they're telling us the the whole new pressure is a little bit lower than that. It's at 490. So it's a little different, Not much different, but it's a little different. And we're starting at -60, so let's say -60 is here, and then let's say that 10�C is over here. It doesn't really matter in terms of spacing. We know that -60 is going to be to the left of -45 and we know 10�C will be to the right.
We know that we're starting out as a solid. So we know we're somewhere within this phase here and we're just traveling from our solid phase and getting to 10�C which is over here. Remember, if we were to basically suction off the different phases, phases of our phase diagram, we'd have our solid, our liquid and our gas. We just went from the solid phase, we skipped the liquid phase and ended up in the gaseous phase.
Remember, going from a solid straight to a gas, we call that sublimation. That would mean that option E is our correct answer.