Chapter 10

Amino acids are the building blocks of the body's worker molecules called proteins. When two amino acids bond together, they do so through the formation of a peptide linkage, and a dipeptide is formed. Consider the following tripeptide formed when three alanine amino acids bond together: What types of interparticle forces could be present in a sample of this tripeptide?

When a person has a severe fever, one therapy used to reduce the fever is an "alcohol rub." Explain how the evaporation of alcohol from a person's skin removes heat energy from the body.

Why is a burn from steam typically much more severe than a burn from boiling water?

Consider the following enthalpy changes: $$\begin{array}{r}{\mathrm{F}}^{-}+\mathrm{HF}⟶{\mathrm{FHF}}^{-}\mathrm{\Delta }H=-155\mathrm{kJ}/\mathrm{mol}\\ {\left({\mathrm{CH}}_3\right)}_2\mathrm{C}=\mathrm{O}+\mathrm{HF}⟶{\left({\mathrm{CH}}_3\right)}_2\mathrm{C}=\mathrm{O}--\mathrm{HF}\\ \mathrm{\Delta }H=-46\mathrm{kJ}/\mathrm{mol}\\ {\mathrm{H}}_2\mathrm{O}(g)+\mathrm{HOH}(g)⟶{\mathrm{H}}_2\mathrm{O}--\mathrm{HOH}(\text{ in ice })\\ \mathrm{\Delta }H=-21\mathrm{kJ}/\mathrm{mol}\end{array}$$ How do the strengths of hydrogen bonds vary with the electronegativity of the element to which hydrogen is bonded? Where in the preceding series would you expect hydrogen bonds of the following type to fall?

Argon has a cubic closest packed structure as a solid. Assuming that argon has a radius of $190.\mathrm{pm}$, calculate the density of solid argon.

Dry nitrogen gas is bubbled through liquid benzene $\left({\mathrm{C}}_6{\mathrm{H}}_6\right)$ at ${20.0}^{\circ }\mathrm{C}$. From $100.0\mathrm{L}$ of the gaseous mixture of nitrogen and benzene, $24.7\mathrm{g}$ benzene is condensed by passing the mixture through a trap at a temperature where nitrogen is gaseous and the vapor pressure of benzene is negligible. What is the vapor pressure of benzene at $20.0{}^{\circ }\mathrm{C}$ ?

A $20.0-\mathrm{g}$ sample of ice at $-{10.0}^{\circ }\mathrm{C}$ is mixed with $100.0\mathrm{g}$ water at ${80.0}^{\circ }\mathrm{C}$. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of ${\mathrm{H}}_2\mathrm{O}(s)$ and ${\mathrm{H}}_2\mathrm{O}(l)$ are $2.03$ and $4.18\mathrm{J}/\mathrm{g}\cdot {}^{\circ }\mathrm{C}$, respectively, and the enthalpy of fusion for ice is $6.02\mathrm{kJ}/\mathrm{mol}$.

In regions with dry climates, evaporative coolers are used to cool air. A typical electric air conditioner is rated at $1.00\times {10}^4\mathrm{Btu}/\mathrm{h}$ (1 Btu, or British thermal unit $=$ amount of energy to raise the temperature of $1\mathrm{lb}$ water by $1^{\circ }\mathrm{F}).$ What quantity of water must be evaporated each hour to dissipate as much heat as a typical electric air conditioner?

The critical point of ${\mathrm{NH}}_3$ is ${132}^{\circ }\mathrm{C}$ and $111\mathrm{atm}$, and the critical point of ${\mathrm{N}}_2$ is $-{147}^{\circ }\mathrm{C}$ and 34 atm. Which of these substances cannot be liquefied at room temperature no matter how much pressure is applied? Explain.

When 1 mol benzene is vaporized at a constant pressure of $1.00$ atm and at its boiling point of $353.0\mathrm{K},30.79\mathrm{kJ}$ of energy (heat) is absorbed and the volume change is $+28.90\mathrm{L}$. What are $\mathrm{\Delta }E$ and $\mathrm{\Delta }H$ for this process?