Chapter 6, Problem 6.21P

(a)

Interpretation Introduction

Interpretation:

Whether the freezing of water is an exothermic or endothermic is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant but at constant pressure, the $P\Delta V$ work gets eliminated and the change in enthalpy $\left(\Delta H\right)$ is measured.

In the case of a reaction, the change in enthalpy $\left(\Delta H\right)$ is the difference in the energy of the product and reactant. The general expression to calculate $\Delta H$ is,

$\Delta H=H_{\text{Product}}-H_{\text{Reactant}}$ (1)

Here,

$\Delta H$ is the change in enthalpy of the system.

$H_{\text{Product}}$ is the enthalpy of the products.

$H_{\text{Reactant}}$ is the enthalpy of the reactants.

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product. $H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ in the exothermic reactions.

Answer to Problem 6.21P

The freezing of water is an exothermic process.

Explanation of Solution

Freezing of water means the conversion of liquid form of water to solid form. The heat is released in the conversion to solid form.

$H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ so $\Delta H$ of the process is negative and the reaction is exothermic reaction.

Conclusion

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product.

(b)

Interpretation Introduction

Interpretation:

Whether the boiling of water is an exothermic or endothermic is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant but at constant pressure, the $P\Delta V$ work gets eliminated and the change in enthalpy $\left(\Delta H\right)$ is measured.

In the case of a reaction, the change in enthalpy $\left(\Delta H\right)$ is the difference in the energy of the product and reactant. The general expression to calculate $\Delta H$ is,

$\Delta H=H_{\text{Product}}-H_{\text{Reactant}}$ (1)

Here,

$\Delta H$ is the change in enthalpy of the system.

$H_{\text{Product}}$ is the enthalpy of the products.

$H_{\text{Reactant}}$ is the enthalpy of the reactants.

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product. $H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ in the exothermic reactions.

Answer to Problem 6.21P

The boiling of water is an endothermic process.

Explanation of Solution

The boiling of water means the conversion of liquid form of water to gaseous form. The heat is absorbed in the conversion to gaseous form.

$H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ so $\Delta H$ of the process is positive and the reaction is endothermic reaction.

Conclusion

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product.

(c)

Interpretation Introduction

Interpretation:

Whether the digestion of food is an exothermic or endothermic is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant but at constant pressure, the $P\Delta V$ work gets eliminated and the change in enthalpy $\left(\Delta H\right)$ is measured.

In the case of a reaction, the change in enthalpy $\left(\Delta H\right)$ is the difference in the energy of the product and reactant. The general expression to calculate $\Delta H$ is,

$\Delta H=H_{\text{Product}}-H_{\text{Reactant}}$ (1)

Here,

$\Delta H$ is the change in enthalpy of the system.

$H_{\text{Product}}$ is the enthalpy of the products.

$H_{\text{Reactant}}$ is the enthalpy of the reactants.

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product. $H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ in the exothermic reactions.

Answer to Problem 6.21P

The digestion of food is an exothermic process.

Explanation of Solution

The digestion of food involves breakage of the food by the body. The energy is released in the process of breaking.

$H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ so $\Delta H$ of the process is negative and the reaction is exothermic reaction.

Conclusion

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product.

(d)

Interpretation Introduction

Interpretation:

Whether the running of person is an exothermic or endothermic is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant but at constant pressure, the $P\Delta V$ work gets eliminated and the change in enthalpy $\left(\Delta H\right)$ is measured.

In the case of a reaction, the change in enthalpy $\left(\Delta H\right)$ is the difference in the energy of the product and reactant. The general expression to calculate $\Delta H$ is,

$\Delta H=H_{\text{Product}}-H_{\text{Reactant}}$ (1)

Here,

$\Delta H$ is the change in enthalpy of the system.

$H_{\text{Product}}$ is the enthalpy of the products.

$H_{\text{Reactant}}$ is the enthalpy of the reactants.

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product. $H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ in the exothermic reactions.

Answer to Problem 6.21P

The running of person is an exothermic process.

Explanation of Solution

When a person runs heat is released from the body as the muscles perform work to run.

$H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ so $\Delta H$ of the process is negative and the reaction is exothermic reaction.

Conclusion

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product.

(e)

Interpretation Introduction

Interpretation:

Whether the growing of person is an exothermic or endothermic is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant but at constant pressure, the $P\Delta V$ work gets eliminated and the change in enthalpy $\left(\Delta H\right)$ is measured.

In the case of a reaction, the change in enthalpy $\left(\Delta H\right)$ is the difference in the energy of the product and reactant. The general expression to calculate $\Delta H$ is,

$\Delta H=H_{\text{Product}}-H_{\text{Reactant}}$ (1)

Here,

$\Delta H$ is the change in enthalpy of the system.

$H_{\text{Product}}$ is the enthalpy of the products.

$H_{\text{Reactant}}$ is the enthalpy of the reactants.

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product. $H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ in the exothermic reactions.

Answer to Problem 6.21P

The growing of person is an endothermic process.

Explanation of Solution

When a person grows it consums food to perform functions of body. The food calories is converted to tissues present in body so energy is consumed.

$H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ so $\Delta H$ of the process is positive and the reaction is endothermic reaction.

Conclusion

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product.

(f)

Interpretation Introduction

Interpretation:

Whether the chopping of wood is an exothermic or endothermic is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant but at constant pressure, the $P\Delta V$ work gets eliminated and the change in enthalpy $\left(\Delta H\right)$ is measured.

In the case of a reaction, the change in enthalpy $\left(\Delta H\right)$ is the difference in the energy of the product and reactant. The general expression to calculate $\Delta H$ is,

$\Delta H=H_{\text{Product}}-H_{\text{Reactant}}$ (1)

Here,

$\Delta H$ is the change in enthalpy of the system.

$H_{\text{Product}}$ is the enthalpy of the products.

$H_{\text{Reactant}}$ is the enthalpy of the reactants.

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product. $H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ in the exothermic reactions.

Answer to Problem 6.21P

The chopping of wood is an endothermic process.

Explanation of Solution

Chopping of wood requires energy as the work is done to chop the wood. Mechanical work is done in chhoping so theheat is absorbed.

$H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ so $\Delta H$ of the process is positive and the reaction is endothermic reaction.

Conclusion

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product.

(g)

Interpretation Introduction

Interpretation:

Whether the heating with a furnace is an exothermic or endothermic is to be determined.

Concept introduction:

The internal energy of a process is the summation of the kinetic energy and potential energy associated with the process. In the case of a reaction, the change in internal energy $\left(\Delta E\right)$ is the difference in the energy of the product and reactant but at constant pressure, the $P\Delta V$ work gets eliminated and the change in enthalpy $\left(\Delta H\right)$ is measured.

In the case of a reaction, the change in enthalpy $\left(\Delta H\right)$ is the difference in the energy of the product and reactant. The general expression to calculate $\Delta H$ is,

$\Delta H=H_{\text{Product}}-H_{\text{Reactant}}$ (1)

Here,

$\Delta H$ is the change in enthalpy of the system.

$H_{\text{Product}}$ is the enthalpy of the products.

$H_{\text{Reactant}}$ is the enthalpy of the reactants.

Endothermic reactions are the reactions in which energy in the form of the heat or light is absorbed by the reactant for the formation of product. $H_{\text{Product}}$ is greater than $H_{\text{Reactant}}$ in the endothermic reactions.

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product. $H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ in the exothermic reactions.

Answer to Problem 6.21P

The heating with a furnace is an exothermic process.

Explanation of Solution

The heating of the furnance release heat as the temperature of the system increases. The temperature increase due to the reaction in furnance releases energy to the surrounding.

$H_{\text{Reactant}}$ is greater than $H_{\text{Product}}$ so $\Delta H$ of the process is negative and the reaction is exothermic reaction.

Conclusion

Exothermic reactions are the reactions in which energy in the form of the heat or light is released with the product.