Chapter 6, Problem 6.85P

(a)

Interpretation Introduction

Interpretation:

$\Delta H_{\text{rxn}}^{°}$ for the dilution of $1\text{mol}$ of sulphuric acid is to be determined.

Concept introduction:

The standard enthalpy of reaction is calculated by the summation of standard enthalpy of formation of the product minus the summation of standard enthalpy of formation of product at the standard conditions. The formula to calculate the standard enthalpy of reaction $\left(\Delta H_{\text{rxn}}^{°}\right)$ is as follows:

$\Delta H_{\text{rxn}}^{°}=\sum m\Delta H_{\text{f (products)}}^{°}-\sum m\Delta H_{\text{f (reactants)}}^{°}$

Here, m and n are the stoichiometric coefficients of reactants and product in the balanced chemical equation.

(b)

Interpretation Introduction

Interpretation:

The final temperature when the initial temperature of the calorimeter is $25°\text{C}$ is to be determined.

Concept introduction:

Heat capacity $\left(C\right)$ of a material is the quantity to measure the heat needed to raise the temperature of a substance by $1\text{K}$. The formula to calculate heat required is as follows:

$q=\left(C\right)\left(\Delta T\right)$ (2)

Here,

$\Delta T$ is the temperature difference.

$q$ is the heat released or absorbed.

$C$ is the heat capacity of the substance.

Specific heat capacity $\left(c\right)$ of a substance is the quantity to measure the heat needed to raise the temperature of $1\text{g}$ of a substance by $1\text{K}$. The formula to calculate heat required is as follows:

$q=\left(\text{mass}\right)\left(c\right)\left(\Delta T\right)$ (3)

Here,

$\Delta T$ is the temperature difference.

$q$ is the heat released or absorbed.

$c$ is the specific heat capacity of the substance.

(c)

Interpretation Introduction

Interpretation:

The reason for the addition of acid to water rather than water to acid on the basis of heat capacity is to be explained.

Concept introduction:

Heat capacity $\left(C\right)$ of a material is the quantity to measure the heat needed to raise the temperature of a substance by $1\text{K}$. The formula to calculate heat required is as follows:

$q=\left(C\right)\left(\Delta T\right)$ (2)

Here,

$\Delta T$ is the temperature difference.

$q$ is the heat released or absorbed.

$C$ is the heat capacity of the substance.

Specific heat capacity $\left(c\right)$ of a substance is the quantity to measure the heat needed to raise the temperature of $1\text{g}$ of a substance by $1\text{K}$. The formula to calculate heat required is as follows:

$q=\left(\text{mass}\right)\left(c\right)\left(\Delta T\right)$ (3)

Or,

$\Delta T=\frac{q}{\left(\text{mass}\right)\left(c\right)}$ (7)

Here,

$\Delta T$ is the temperature difference.

$q$ is the heat released or absorbed.

$c$ is the specific heat capacity of the substance.