Question

http://www.dabbleboard.com/draw okay so go to this link and see the document. I need help with number 8. above what temp is it imposible to liquify this substance no matter what the pressure? and number 9. at what temp and pressure do all three phases coexist? and number 10. is the density of the solid greater than or less than the density of the liquid? and last number 11. would an increase in pressure cause this subsatnce to freeze or melt? use the link to look at the diagram.

Answer 1

You've already correctly identified the critical point. This is the point above which a particular phase boundary ceases to exist. All you need to is read off the temperature at the critical point.

Likewise, you already have the triple point identified. This question is just checking that you understand the meaning of the term 'triple point'.

To answer question 10, you have to think about arrangement of atoms in solids and liquids. In solids, atoms are closely packed in fairly static, regular arrangements. In liquids, the atoms have a bit more energy and so move and jostle around a lot more.

If you follow the dotted line at 60 degrees C u you can see what happens as pressure is increased. At 0.5 atmospheres, you are still in region B but as you go up you cross over to region C. Now just think what phase boundary you have just crossed.