The normal melting point of benzene, $\mathrm{C}_6 \mathrm{H}_6$, is $5.5^{\circ} \mathrm{C}$. For the process of melting, what is the sign of each of the following?
$\Delta G^{\circ}$ at $5.5^{\circ} \mathrm{C}$

Benzene, $\mathrm{C}_0 \mathrm{H}_6$, is an organic liquid that freezes at $5.5{ }^{\circ} \mathrm{C}$ ($\blacktriangleleft$ Figure 12.1) to form beautiful, feather-like crystals. How much energy is evolved as heat when $15.5 \mathrm{~g}$ of benzene freezes at $5.5^{\circ} \mathrm{C}$ ? (The enthalpy of fusion of benzene is $9.95 \mathrm{~kJ} / \mathrm{mol}$.) If the $15.5-\mathrm{g}$ sample is remelted, again at $5.5^{\circ} \mathrm{C}$, what quantity of energy is required to convert it to a liquid?

The molar heat of fusion of benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ is 9.92 kJ/mol. Its molar heat of vaporization is 30.7 kJ/mol. Calculate the heat required to melt 8.25 g benzene at its normal melting point. Calculate the heat required to vaporize 8.25 g benzene at its normal boiling point. Why is the heat of vaporization more than three times the heat of fusion?

Benzene, ${C}_6 {H}_6$, is an organic liquid that freezes at $5.5^{\circ} {C}$ to form beautiful, feather-like crystals. How much energy is evolved as heat when 15.5 g of benzene freezes at $5.5^{\circ} {C}$ ? (The enthalpy of fusion of benzene is 9.95 kJ / mol.) If the 15.5-g sample is remelted, again at $5.5^{\circ} {C}$, what quantity of energy is needed to convert it to a liquid?

The melting point of benzene is $5.5^{\circ} \mathrm{C}$. Predict the signs of $\Delta H, \Delta \mathrm{S}$, and $\Delta G$ for melting of benzene at: (a) $0^{\circ} \mathrm{C}$ (b) $15^{\circ} \mathrm{C}$

The melting point of benzene is $5.5^{\circ} \mathrm{C}$. Predict the signs of $\Delta H, \Delta S$, and $\Delta G$ for melting of benzene at:
(a) $0^{\circ} \mathrm{C}$
(b) $15^{\circ} \mathrm{C}$

The melting point of benzene is 5.5 $\degree$ C and its boiling point is 80.1 $\degree$ C. Sketch a heating curve for benzene from 0 $\degree$ C to 100 $\degree$ C. What happens on the curve at 5.5 $\degree$ C?

Explain why each of the following statements is incorrect.
Entropy increases in all spontaneous reactions.

Explain why each of the following statements is incorrect.
Reactions with a negative free energy change $\left(\Delta_{\mathrm{r}} G^{\circ}<0\right)$ are product-favored and occur with the rapid transformation of reactants to products.

Analyze equilibrium constant expressions by completing the following statements. The concentration of liquid water in the denominator of an equilibrium constant expression is considered to be ____ in dilute aqueous solutions. Therefore, liquid water can be ________ K$_{eq}$ to give a new equilibrium constant, K$_{a}$, For weak acids, the equilibrium _______ of the _______ in the numerator tends to be small compared to the equilibrium _______ of the _____ in the denominator. The weakest acids have the _____ K$_{a}$ values because their solutions have the highest concentrations of ______ acid molecules.

Write the dissociation reaction and the corresponding $K_{\mathrm{a}}$ equilibrium expression for each of the following acids in water. $\mathrm{HCN}$

Propane ($\ce{C3H8}$) burns according to the following balanced equation:

$$\ce{C3H8(g) + 5O2(g)} \rightarrow \ce{3CO2(g) + 4H2O(g)}$$

Calculate $\Delta H_{\text{rxn}}^\circ$ for this reaction using standard enthalpies of formation. The standard enthalpy of formation of gaseous propane is -103.9 kJ/mol.

Ammonia can be synthesized by this reaction:

$$\ce{3H2(g) + N2(g)} \rightarrow \ce{ 2NH3(g)}$$

What maximum amount of ammonia in grams can be synthesized from 25.2 g of $\ce{N2}$ and 8.42 g of $\ce{H2}$? Express your answer in grams to one decimal place.

Nitrogen and hydrogen combine at high temperature, in the presence of a catalyst, to produce ammonia:

$$\ce{N2(g) + 3H2(g) \rightarrow 2NH3(g)}$$

Assume 0.280 mol of N$_2$ and 0.884 mol of H$_2$ are present initially. After complete reaction, how many moles of ammonia are produced? Which reactant is the limiting one?