A water strider (which can walk on water) has legs that

What is electronegativity, and how does it affect interactions between water molecules? Review p. 39 and Figure 2.13.

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

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

Label a hydrogen bond and a polar covalent bond in this figure. How many hydrogen bonds can each water molecule make?

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

Explain the saying Its not the heat; its the humidity.

How can the freezing of water crack boulders?

The concentration of the appetite-regulating hormone ghrelin is about 1.3 1010M in a fasting person. How many molecules of ghrelin are in 1 L of blood?

A water strider (which can walk on water) has legs that are coated with a hydrophobic substance. What might be the benefit? What would happen if the substance were hydrophilic?

Describe how different types of solutes dissolve in water. Explain the difference between a solution and a colloid.

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 S H Cl. What is the pH of 0.01 M HCl? 3

Acetic acid (CH3COOH) can be a buffer, similar to carbonic acid. Write the dissociation reaction, identifying the acid, base, Hacceptor, and Hdonor.

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 from question 3 to explain the result.

Explain how increasing amounts of CO2 dissolving in the ocean leads to ocean acidification. How does this change in pH affect carbonate ion concentration and the rate of calcification?

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature? a. waters change in density when it condenses b. waters 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. waters high surface tension

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.

Which of the following is a hydrophobic material? a. paper d. sugar b. table salt e. pasta c. wax

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

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake? a. 4.0 M b. 1010 M c. 104 M d. 104 M e. 4%

What is the hydroxide ion concentration of the lake described in question 5? a. 1010 M b. 104 M c. 107 M d. 1014M e. 10 M LE

A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what would be the approximate increase in the temperature of the water? (Note: A liter of cold water weighs about 1 kg.) a. 50C b. 5C c. 1C d. 100C e. 10C

How many grams of acetic acid (C2H4O2) 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 12 for carbon, 1 for hydrogen, and 16 for oxygen.) a. 10 g b. 0.1 g c. 6.0 g d. 60 g e. 0.6 g

Draw the hydration shells that form around a potassium ion and a chloride ion when potassium chloride (KCl) dissolves in water. Label the positive, negative, and partial charges on the atoms.

What do global warming (see Chapter 1, p. 6) and ocean acidification have in common?

In agricultural areas, farmers pay close attention to the weather forecast. Right before a predicted overnight freeze, farmers 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.

This chapter explains how the emergent properties of water contribute to the suitability of the environment for life. Untilfairly recently, scientists assumed that other physical requirements for life included a moderate range of temperature, pH, atmospheric pressure, and salinity, as well as low levels of toxic chemicals. That view has changed with the discovery of organisms known as extremophiles, which have been found flourishing in hot, acidic sulfur springs, around hydrothermal vents deep in the ocean, and in soils with high levels of toxic metals. Why would astrobiologists be interested in studying extremophiles? What does the existence of life in such extreme environments say about the possibility of life on other planets?

Design a controlled experiment to test the hypothesis that acid precipitation inhibits the growth of Elodea, a common freshwater plant (see Figure 2.19, p. 43).

In a study reported in 2000, C. Langdon and colleagues used an artificial coral reef system to test the effect of carbonate concentration on the rate of calcification by reef organisms. The graph on the right presents one set of their results. Describe what these data show. How do these results relate to the ocean acidification that is associated with increasing atmospheric CO2 levels?

Agriculture, industry, and the growing populations of cities all compete, through political influence, for water. If you were in charge of water 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?

Several emergent properties of water contribute to the suitability of the environment for life. In a short essay (100150 words), describe how the ability of water to function as a versatile solvent arises from the structure of water molecules.