Chapter U5.99, Problem 4E

Interpretation Introduction

Interpretation: The amount of energy transferred from the ring when gold solidifies is to be calculated and the temperature at which all atoms of gold atoms become solid is to be determined.

Concept introduction: Fusion is the process in which conversion of solid to liquid takes place. The quantity of heat which is absorbed by a solid at the melting point which results conversion of solid into liquid completely is termed as heat of fusion.

Answer to Problem 4E

Amount of energy transferred to the ring is $\text{92}\text{.4}\text{cal}$ and the temperature at which all atoms of gold becomes solid is $1064°\text{C}$ .

Explanation of Solution

The heat of fusion of gold is $15.4\text{cal}\text{/}\text{g}$ and mass of the sample is 6 g. So, the energy of fusion can be calculated as:

  $\begin{array}{c}\text{Energy}\text{of}\text{fusion}\text{=}\text{Heat}\text{of}\text{fusion}\text{of}\text{gold}\times \text{mass}\text{of}\text{sample}\\ \text{=15}\text{.4 }\text{cal}/\text{g}\times \text{6}\text{g}\\ \text{=92}\text{.4}\text{cal}\end{array}$

So, the amount of energy transferred when the ring solidifies is $\text{92}\text{.4}\text{cal}$ .

The melting point of gold is $1064°\text{C}$ .As the melting point and freezing point of gold is equal, the freezing point of gold is $1064°\text{C}$ .

Conclusion

The melting point and freezing point of gold is equal.