Answer to Question #181290 in General Chemistry for Joshua

Question

1) How energy change affects the phase and temperature of a material?

2) What are the phase changes involved in heating curve for substances? When do they occur?

3) Why do the temperature of liquid remain unchanged right around 100°C even though water was continously heated?

4) In which cup do water cool fastest? What do you think is the relationship of material used in cup to the temperature change in water?

5) What are the phases and phase challenge involve in cooling curve a water? When do they occur?

Answer 1

1.Energy is required to change the phase of a substance, such as the energy to break the bonds between molecules in a block of ice so it may melt. During a phase change energy my be added or subtracted from a system, but the temperature will not change.

2.A heating curve graphically represents the phase transitions that a substance undergoes as heat is added to it.The first change of phase is melting, during which the temperature stays the same while water melts. The second change of phase is boiling, as the temperature stays the same during the transition to gas.

3.The temperature remains constant during boiling of water even though heat is supplied constantly because all the heat energy provided is used up in changing the state of water from liquid to gaseous water vapour.

4.The air cooled down the fastest. The sand and soil cooled up at similar rates. The water cooled down the slowest as well.

5.A cooling curve is a line graph that represents the change of phase of matter, typically from a gas to a solid or a liquid to a solid. The independent variable (X-axis) is time and the dependent variable (Y-axis) is temperature. Below is an example of a cooling curve used in castings.