Chapter 14, Problem 15A

Interpretation Introduction

Interpretation: The meaning of different portion in the cooling curve of water has to be discussed.

Concept introduction: Heating curves represents the change in temperature as a substance is heated. Cooling curves represents the change in temperature as a substance is cooled. Heating and cooling curves have horizontal flat parts that shows the phases changes.

Answer to Problem 15A

The phase changes are given by the flat portions of the curve whereas, the slope represents the changes in temperature.

Explanation of Solution

The heating-cooling curve of water is,

The x-axis represents the amount of heat added at constant rate and the temperature in $\left({}^{\text{o}}\text{C}\right)$ is given in the y-axis.

  

Figure 1: Heating-cooling curve of water

The heating curve (addition of energy) goes from left to right in the above graph and the cooling curve (removal of energy) goes from right to left.

The flat portions of the curve represent the changes in phases and the slope of the curve represents the changes in temperature.

Conclusion

The changes in phase are given by the flat portions of the curve whereas, the slope represents the changes in temperature.