Chapter 12

Polar Molecules Use relative differences in electronegativity to label the ends of the polar molecules listed as partially positive or partially negative. $$\quad \text { a. HF }\quad \text { b. HBr } \quad \text { c.NO } \quad \text { d. } C O$$

Draw the structure of the dipole-dipole interaction between two molecules of carbon monoxide.

Decide which of the substances listed can form hydrogen bonds. $$\mathbf{a} \cdot \mathrm{H}_{2} \mathrm{O} \quad \text { b. } \mathrm{H}_{2} \mathrm{O}_{2} \quad \text { c. HF } \quad \text { d. } \mathrm{NH}_{3}$$

What is surface tension, and what conditions must exist for it to occur?

Explain why the surface of water in a graduated cylinder is curved.

Which liquid is more viscous at room temperature, water or molasses? Explain.

What is the difference between a network solid and an ionic solid?

Explain why most metals bend when struck but most ionic solids shatter.

List the types of crystalline solids that are usually good conductors of heat and electricity.

How does the strength of a liquid's intermolecular forces affect its viscosity?

Explain why water has a higher surface tension than benzene, whose molecules are nonpolar.

Compare the number of particles in one unit cell for each of the following types of unit cells. $$ \begin{array}{l}{\text { a. simple cubic }} \\ {\text { b. body-centered cubic }}\end{array} $$

Predict which solid is more likely to be amorphous- one formed by cooling a molten material over 4 h at room temperature or one formed by cooling a molten material quickly in an ice bath.

Explain why ice floats in water but solid benzene sinks in liquid benzene. Which behavior is more "normal"?

How does sublimation differ from deposition?

Compare boiling and evaporation.

Define the term melting point.

Explain the relationships among vapor pressure, atmospheric pressure, and boiling point.

Snow Why does a pile of snow slowly shrink even on days when the temperature never rises above the freezing point of water?

Use the kinetic-molecular theory to explain why both gases and liquids are fluids.

Use intermolecular forces to explain why oxygen is a gas at room temperature and water is a liquid.

Use the kinetic-molecular theory to explain why gases are easier to compress than liquids or solids.

At \(25^{\circ} \mathrm{C}\) and a pressure of \(760 \mathrm{mm} \mathrm{Hg},\) the density of mercury is 13.5 \(\mathrm{g} / \mathrm{mL}\) ; water at the same temperature and pressure has a density of 1.00 \(\mathrm{g} / \mathrm{mL}\) . Explain this difference in terms of intermolecular forces and the kinetic-molecular theory.

If two identical containers each hold the same gas at the same temperature but the pressure inside one container is exactly twice that of the other container, what must be true about the amount of gas inside each container?

List three types of intermolecular forces.

When solid sugar crystals are dissolved in a glass of water, they form a clear homogeneous solution in which the crystals are not visible. If the beaker is left out at room temperature for a few days, the crystals reappear in the bottom and on the sides of the glass. Is this an example of freezing?

Hypothesize What type of crystalline solid do you predict would best suit the following needs? $$ \begin{array}{l}{\text { a. a material that can be melted and reformed at a low }} \\ {\text { temperature }} \\ {\text { b. a material that can be drawn into long, thin wires }} \\ {\text { c. a material that conducts electricity when molten }} \\ {\text { d. an extremely hard material that is nonconductive }}\end{array} $$

Compare and Contrast An air compressor uses energy to squeeze air particles together. When the air is released, it expands, allowing the energy to be used for purposes such as gently cleaning surfaces without using a more abrasive liquid or solid. Hydraulic systems essentially work the same way, but involve compression of liquid water rather than air. What do you think are some advantages and disadvantages of these two types of technology?

Apply A solid being heated stays at a constant temperature until it is completely melted. What happens to the heat energy put into the system during that time?

Communicate Which process-effusion or diffusion- is responsible for your being able to smell perfume from an open bottle that is located across the room from you? Explain.

Infer A laboratory demonstration involves pouring bromine vapors, which are a deep red color, into a flask of air and then tightly sealing the top of the flask. The bromine is observed to first sink to the bottom of the beaker. After several hours have passed, the red color is distributed equally throughout the flask. $$ \begin{array}{l}{\text { a. Is bromine gas more or less dense than air? }} \\\ {\text { b. Would liquid bromine diffuse more or less quickly }} \\ {\text { than gaseous bromine after you pour it into another }} \\ {\text { liquid? }}\end{array} $$

Analyze Use your knowledge of intermolecular forces to predict whether ammonia (NH \(_{3} )\) or methane \(\left(\mathrm{CH}_{4}\right)\) will be more soluble in water.

Evaluate List three changes that require energy and three that release energy.

Identify each of the following as an element, a compound, a homogeneous mixture, or a heterogeneous mixture. (Chapter 3\()\) $$ \begin{array}{ll}{\text { a. air }} & {\text { d. ammonia }} \\ {\text { b. blood }} & {\text { e. mustard }} \\ {\text { c. antimony }} & {\text { f. water }}\end{array} $$

You are given two clear, colorless aqueous solutions. You are told that one solution contains an ionic compound, and one contains a covalent compound. How could you determine which is an ionic solution and which is a covalent solution? (Chapter 8)

Which branch of chemistry would most likely study matter and phase changes? (Chapter 1) $$ \begin{array}{ll}{\text { a. biochemistry }} & {\text { c. physical chemistry }} \\ {\text { b. organic chemistry }} & {\text { d. polymer chemistry }}\end{array} $$

What type of reaction is the following? (Chapter 9) $$ \mathrm{K}_{2} \mathrm{CO}_{3}(\mathrm{aq})+\mathrm{BaCl}_{2}(\mathrm{aq}) \rightarrow 2 \mathrm{KCl}(\mathrm{aq})+\mathrm{BaCO}_{3}(\mathrm{s}) $$ $$ \begin{array}{ll}{\text { a. combustion }} & {\text { c. single-replacement }} \\\ {\text { b. double-replacement }} & {\text { d. synthesis }}\end{array} $$

Which chemist produced the first widely used and accepted periodic table? (Chapter 6\()\) $$ \begin{array}{ll}{\text { a. Dmitri Mendeleev }} & {\text { c. John Newlands }} \\ {\text { b. Henry Moseley }} & {\text { d. Lothar Meyer }}\end{array} $$

Musk is the basic ingredient of many perfumes, soaps, shampoos, and even foods such as chocolates, licorice, and hard candies. Both synthetic and natural musk molecules have high molecular weights compared to other perfume ingredients, and as a result, have a slower rate of diffusion, assuring a slow, sustained release of fragrance. Write a report on the chemistry of perfume ingredients, emphasizing the importance of diffusion rate as a property of perfume.

Birthstones Find out what your birthstone is and write a brief report about the chemistry of that gem. Find out its chemical composition, which category its unit cell is in, how hard and durable it is, and what its approximate cost is at present.

Propane gas is a commonly used heating fuel for gas grills and homes. However, it is not packaged as a gas. It is liquefied and referred to as liquid propane or "LP gas." Make a poster explaining the advantages and disadvantages of storing and transporting propane as a liquid rather than a gas.

Other States of Matter Research and prepare an oral report about one of the following topics: plasma, superfluids, fermionic condensate, or Bose-Einstein condensate. Share your report with your classmates and prepare a visual aid that can be used to explain your topic.

Jodine Solid iodine that is left at room temperature subli- mates from a solid to a gas. But when heated quickly, a different process takes place, as described here. "About 1 g of iodine crystals is placed in a sealed glass ampoule and gently heated on a hot plate. A layer of purple gas is formed at the bottom, and the iodine liquefies. If one tilts the tube, this liquid flows along the wall as a narrow stream and solidifies very quickly". $$\begin{array}{l}{\text { Why does solid iodine sublime readily? Use your }} \\\ {\text { knowledge of intermolecular forces to explain. }}\end{array}$$

Jodine Solid iodine that is left at room temperature subli- mates from a solid to a gas. But when heated quickly, a different process takes place, as described here. "About 1 g of iodine crystals is placed in a sealed glass ampoule and gently heated on a hot plate. A layer of purple gas is formed at the bottom, and the iodine liquefies. If one tilts the tube, this liquid flows along the wall as a narrow stream and solidifies very quickly". $$\begin{array}{l}{\text { Why is liquid iodine not usually visible if crystals are }} \\ {\text { heated in the open air? }}\end{array}$$

Jodine Solid iodine that is left at room temperature subli- mates from a solid to a gas. But when heated quickly, a different process takes place, as described here. "About 1 g of iodine crystals is placed in a sealed glass ampoule and gently heated on a hot plate. A layer of purple gas is formed at the bottom, and the iodine liquefies. If one tilts the tube, this liquid flows along the wall as a narrow stream and solidifies very quickly". $$\begin{array}{l}{\text { Why is it necessary to use a sealed ampoule in this }} \\ {\text { investigation? }}\end{array}$$