The surface ofthe planet Mars has many landscape features

What is electronegativity, and how does it affect interactions between water molecules?

Why is it unlikely that two neighboring water mole cules would be arranged like this?

What would be the effect on the properties ofthe water molecule if oxygen and hydrogen had equal electronegativity?

Describe how properties ofwater contribute to the upward movement ofwater in a tree.

Explain the saying ~It's not the heat; it's the humidity.~

How can the freezing ofwater crack boulders?

If you were a pharmacist, how would you make a 0.5- molar (0.5 M) solution ofsodium chloride (NaCl)? (The atomic mass of Na is 23 daltons and that ofCl is 35.5 daltons.)

A water strider's legs (see Figure 3.4) are coated with a hydrophobic substance. \'V'hat might be the benefit? \'V'hat would happen ifthe substance were hydrophilic?

Compared with a basic solution at pH 9, the same volume of an acidic solution at pH 4 has _ times as many hydrogen ions (H+)

HCl is a strong acid that dissociates in water: HCl- H+ + Cl-. What is the pH of 0.01 M HCl?

Acetic acid (CH3COOH) can be a buffer, similar to carbonic acid. Write the dissociation reaction, identifying the acid, base, H+ acceptor, and H+ donor.

Given a liter of pure water and a liter solution of acetic acid, what would happen to the pH if you added 0.01 mol of a strong acid to each? Use the reaction equation to explain the result

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability ofsweat to lower body temperature? a. water's change in density when it condenses b. water's ability to dissolve molecules in the air c. the release of heat by the formation of hydrogen bonds d. the absorption of heat by the breaking of hydrogen bonds e. water's high surface tension

A slice of pizza has 500 kca!. Ifwe could burn the pizza and use all the heat to warm a 5O-L container of cold water, what would be the approximate increase in the temperature ofthe water? (Note; A liter of cold water weighs about 1kg.) a. SO'C d. lOO'C b. S'C e. I'C c. IO'C

The bonds that are broken when water vaporizes are a. ionic bonds. b. hydrogen bonds between water molecules. c. covalent bonds between atoms within water molecules. d. polar covalent bonds. e. nonpolar covalent bonds.

\Vhich ofthe following is a hydrophobic material? a. paper d. sugar b. table salt e. pasta c. wax

We can be sure that a mole oftable sugar and a mole ofvitamin C are equal in their a. mass in daltons. b. mass in grams. c. number of molecules d. number of atoms. e. volume.

How many grams of acetic acid (C2H4~) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? (Note: The atomic masses, in daltons, are approximately 12for carbon, I for hydrogen, and 16 for oxygen.) a. 10.0 g d. 60.0 g b. 0.1 g e. 0.6 g c. 6.0 g

Measurements show that the pH ofa particular lake is 4.0. What is the hydrogen ion concentration ofthe lake? a.4.0M d. 104 M b. 10- 10 M e. 4% c. 10-4 M

\X'hat is the hydroxide ion concentration ofthe lake described in question 7? a. 10-7 M b. 10-4 M c. 10- 10 M d. 10- 14 M e. 10M

Draw three water molecules, using space-filling models, and label the atoms. Draw solid lines to indicate covalent bonds and dotted lines for hydrogen bonds. Add partial-charge labels as appropriate.

The surface ofthe planet Mars has many landscape features reminiscent ofthose formed by flowing water on Earth, including what appear to be meandering channels and outwash areas. In 2004, images Surtace of Marl Surface of Earth of Meridiani Planum on Mars taken by NASA's Opportunity rover suggested that liquid water was once present on its surface. For example, one image (left, above) shows polygonal fractures in the rock. Similar fracture patterns in rocks on Earth's surface (above, right) correlate with the earlier presence ofwater. Ice exists at the Martian poles today, and some scientists suspect a great deal more water may be present beneath the Martian surface. Why has there been so much interest in the presence of water on Mars? Does the presence ofwater make it more likely that life arose there? \Vhat other physical factors might also be important?

Design a controlled experiment to test the hypothesis that acid precipitation inhibits the growth of Elodea, a common freshwater plant (see Figure 2.19).

In agricultural areas, farmers pay close attention to the weather forecast. Right before a predicted overnight freeze, f.umers spray water on crops to protect the plants. Use the properties of water to explain how this method works. Be sure to mention why hydrogen bonds are responsible for this phenomenon.

Agriculture, industry, and the growing populations ofcities all compete, through political influence, for water. Ifyou were in charge ofwater resources in an arid region, what would your priorities be for allocating the limited water supply for various uses? How would you try to build consensus among the different special-interest groups?