Question

h chemistry
name:________________________period___
cooling curve ws
cooling curve for a substance
answer the following questions using the chart above.

1. is energy increasing or decreasing moving right on the x - axis?___________
2. what is the freezing point of the substance?____________________
3. what is the boiling point of the substance?____________________
4. what is the melting point of the substance?______(melting point = freezing

point)

1. what segment represents the range where a solid is being cooled?___________
2. what segment represents the range where a liquid is being cooled?___________
3. what segment represents the range where a vapor is being cooled?___________
4. what segment represents the range where a vapor is condensing?___________
5. what segment represents the range where a liquid is freezing?________________
6. what range(s) show a change in pe?____________________
7. what range(s) show a change in ke?____________________
8. what range represents vaporization?__________(reverse of condensation)
9. what range represents melting?__________(reverse of freezing)

Explanation:

1. On a cooling curve, as time (x - axis) increases, the substance is losing energy, so energy is decreasing.
2. The freezing point is the temperature at which the liquid - solid phase change occurs. On the cooling curve, this is the horizontal line during the liquid - solid transition. From the graph, it is \(90^{\circ}C\).
3. The boiling point is the temperature at which the vapor - liquid phase change occurs during cooling (which is the same as the condensation point). The horizontal line for the vapor - liquid transition gives a temperature of \(150^{\circ}C\).
4. Since melting point = freezing point, it is \(90^{\circ}C\).
5. A solid being cooled is represented by the segment after the substance has completely frozen. That is segment \(EF\).
6. A liquid being cooled (before freezing) is segment \(CD\).
7. A vapor being cooled (before condensation) is segment \(AB\).
8. Vapor condensing (vapor - liquid phase change) is segment \(BC\).
9. Liquid freezing (liquid - solid phase change) is segment \(DE\).
10. Potential energy (PE) changes during phase changes. The horizontal segments \(BC\) (vapor - liquid) and \(DE\) (liquid - solid) show changes in PE.
11. Kinetic energy (KE) changes when the temperature changes. The non - horizontal segments \(AB\) (vapor cooling), \(CD\) (liquid cooling), and \(EF\) (solid cooling) show changes in KE.
12. Vaporization (the reverse of condensation) would have the same temperature as condensation. But on a cooling curve, if we consider the reverse process conceptually (heating curve idea applied), but based on the cooling curve data, the range for vaporization (if we assume the reverse of the condensation segment \(BC\)) is not directly on this cooling curve. However, if we consider the heating - cooling correspondence, the range with the same temperature as condensation (\(150^{\circ}C\)) for vaporization would be a horizontal line (but on a heating curve). But since the problem says "reverse of condensation", and condensation is \(BC\), we assume the answer is related to the temperature of \(BC\). But more accurately, if we consider the cooling curve's reverse (heating), the vaporization range (same as condensation temperature) would be a horizontal line. But based on the given cooling curve data structure, we note that phase - change temperature for vapor - liquid is \(150^{\circ}C\) (from segment \(BC\)).
13. Melting (reverse of freezing) has the same temperature as freezing. The freezing segment is \(DE\) (temperature \(90^{\circ}C\)), so melting (if on a heating curve) would have the same temperature. But on this cooling curve, the segment conceptually (reverse of \(DE\)) is not present. But using the given data and the relation melting point = freezing point (\(90^{\circ}C\)), and if we consider the segment idea (reverse of \(DE\) which is a phase - change segment for freezing), we assume the answer is related to the \(90^{\circ}C\) phase - change.

Answer:

1. Decreasing
2. \(90^{\circ}C\)
3. \(150^{\circ}C\)
4. \(90^{\circ}C\)
5. \(EF\)
6. \(CD\)
7. \(AB\)
8. \(BC\)
9. \(DE\)
10. \(BC\) and \(DE\)
11. \(AB\), \(CD\), \(EF\)
12. \(BC\) (conceptually, as the reverse of condensation which occurs at the same temperature)
13. \(DE\) (conceptually, as the reverse of freezing which occurs at the same temperature)