Chapter 8, Problem 8.8NP

(a)

Interpretation Introduction

Interpretation: The pressure that is requiredto lower the melting temperature of ice by 4.0°C needs to be determined if at 1 atm, ice melts at 273.15 K, ${\text{ΔH}}_{\text{fus}}$ = 6010 J/mol and density of ice is 920 kg/m³. Also, the density of liquid water is 997 kg/m³.

Concept Introduction:All substances can mainly exist in three phases; solid, liquid and gas. These three phases can convert into each other by the application of temperature and pressure such as heating of solid leads to the conversion to liquid and then gaseous state of matter.

Similarly, the gases can be compressed at high pressure to liquefy. The enthalpy change during the fusion of solid to liquid is called as enthalpy of fusion that is denoted as ${\text{ΔH}}_{\text{fus}}$ . Similarly, the enthalpy of vaporization involves in the vaporization of liquid to gas is known as enthalpy of vaporization that is denoted as ${\text{ΔH}}_{\text{vap}}$ .

(b)

Interpretation Introduction

Interpretation: The pressure exerted at the interface of the skate and the ice needs to be determined if the width of the skate that is in contact with the ice gets reduced to $19\times {10}^{-3}\text{cm}$ and length of the contact area is 18 cm with mass 78 kg.

Concept Introduction: All substances can mainly exist in three phases; solid, liquid and gas. These three phases can convert into each other by the application of temperature and pressure such as heating of solid leads to the conversion to liquid and then gaseous state of matter.

Similarly, the gases can be compressed at high pressure to liquefy. The enthalpy change during the fusion of solid to liquid is called as enthalpy of fusion that is denoted as ${\text{ΔH}}_{\text{fus}}$ . Similarly, the enthalpy of vaporization involves in the vaporization of liquid to gas is known as enthalpy of vaporization that is denoted as ${\text{ΔH}}_{\text{vap}}$ .

(c)

Interpretation Introduction

Interpretation: The melting point of ice under the pressure calculated in part (b) needs to be determined.

Concept Introduction: All substances can mainly exist in three phases; solid, liquid and gas. These three phases can convert into each other by the application of temperature and pressure such as heating of solid leads to the conversion to liquid and then gaseous state of matter.

Similarly, the gases can be compressed at high pressure to liquefy. The enthalpy change during the fusion of solid to liquid is called as enthalpy of fusion that is denoted as ${\text{ΔH}}_{\text{fus}}$ . Similarly, the enthalpy of vaporization involves in the vaporization of liquid to gas is known as enthalpy of vaporization that is denoted as ${\text{ΔH}}_{\text{vap}}$ .

(d)

Interpretation Introduction

Interpretation: Whether the melting of ice takes place at the ice-skate interface if the temperature of the ice is -4.0°C or not needs to be explained.

Concept Introduction: All substances can mainly exist in three phases; solid, liquid and gas. These three phases can convert into each other by the application of temperature and pressure such as heating of solid leads to the conversion to liquid and then gaseous state of matter.

Similarly, the gases can be compressed at high pressure to liquefy. The enthalpy change during the fusion of solid to liquid is called as enthalpy of fusion that is denoted as ${\text{ΔH}}_{\text{fus}}$ . Similarly, the enthalpy of vaporization involves in the vaporization of liquid to gas is known as enthalpy of vaporization that is denoted as ${\text{ΔH}}_{\text{vap}}$ .