Bio (Chapter 3)

Assume that acid rain has lowered the pH of a particular lake to pH 4.0. What is the hydroxyl ion concentration of this lake? A) 1 × 10-10 mol of hydroxyl ion per liter of lake water B) 1 × 10-4 mol of hydroxyl ion per liter of lake water C) 10.0 M with regard to hydroxyl ion concentration D) 4.0 M with regard to hydroxyl ion concentration E) both B and D

A

Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O H2CO3. Carbonic acid (H2CO3) is a weak acid. Respiring cells release CO2. What prediction can we make about the pH of blood as that blood first comes in contact with respiring cells? A) Blood pH will decrease slightly. B) Blood pH will increase slightly. C) Blood pH will remain unchanged. D) Blood pH will first increase, then decrease as CO2 combines with hemoglobin. E) Blood pH will first decrease, then increase sharply as CO2 combines with hemoglobin.

A

Hydrophobic substances such as vegetable oil are A) nonpolar substances that repel water molecules. B) nonpolar substances that have an attraction for water molecules. C) polar substances that repel water molecules. D) polar substances that have an affinity for water. E) charged molecules that hydrogen-bond with water molecules.

A

The molecular weight of water is 18 daltons. What is the molarity of 1 liter of pure water? A) 55.6M B) 18M C) 37M D) 0.66M E) 1.0M

A

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10-12 M? A) pH 2 B) pH 4 C) pH 10 D) pH 12 E) pH 14

A

Which of the following solutions has the greatest concentration of hydrogen ions [H +]? A) gastric juice at pH 2 B) vinegar at pH 3 C) tomato juice at pH 4 D) black coffee at pH 5 E) household bleach at pH 12

A

An example of a hydrogen bond is the bond between A) C and H in methane (CH4). B) the H of one water molecule and the O of another water molecule. C) Na+and Cl- in salt. D) the two hydrogen atoms in a molecule of hydrogen gas (H2). E) Mg+and Cl- in MgCl2.

B

At what temperature is water at its densest? A) 0°C B) 4°C C) 32°C D) 100°C E) 212°C

B

The molecular mass of glucose (C6H12O6) is 180 g. Which of the following procedures should you carry out to make a 0.5 M solution of glucose? A) Dissolve 0.5 g of glucose in a small volume of water, and then add more water until the total volume of solution is 1 L. B) Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. C) Dissolve 180 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. D) Dissolve 0.5 g of glucose in 1 L of water. E) Dissolve 180 g of glucose in 1 L of water.

B

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called? A) a covalent bond B) a hydrogen bond C) an ionic bond D) a hydrophilic bond E) a hydrophobic bond

B

Which of the following effects is produced by the high surface tension of water? A) Lakes dont freeze solid in winter, despite low temperatures. B) A water strider can walk across the surface of a small pond. C) Organisms resist temperature changes, although they give off heat due to chemical reactions. D) Water can act as a solvent. E) The pH of water remains exactly neutral.

B

Which of the following ionizes completely in solution and is considered to be a strong acid? A) NaOH B) HCl C) NH3 D) H2CO3 E) CH3COOH

B

Which of the following takes place as an ice cube cools a drink? A) Molecular collisions in the drink increase. B) Kinetic energy in the drink decreases. C) A calorie of heat energy is transferred from the ice to the water of the drink. D) The specific heat of the water in the drink decreases. E) Evaporation of the water in the drink increases.

B

A given solution contains 0.0001(10-4) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution? A) acidic: H+ acceptor B) basic: H+ acceptor C) acidic: H+ donor D) basic: H+ donor E) neutral

C

If the pH of a solution is increased from pH 5 to pH 7, it means that the A) concentration of H+ is twice (2X) what it was at pH 5. B) concentration of H+ is half (1/2) what it was at pH 5. C) concentration of OH- is 100 times greater than what it was at pH 5. D) concentration of OH- is one-hundredth (0.01X) what it was at pH 5. E) concentration of H+ is 100 times greater and the concentration of OH- is one-hundredth what they were at pH 5.

C

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by A) hydrogen bonds. B) nonpolar covalent bonds. C) polar covalent bonds. D) ionic bonds. E) van der Waals interac

C

Pure, freshly-distilled water has a pH of 7. This means that A) there are no H+ ions in the water. B) there are no OH- ions in the water. C) the concentration of H+ ions in the water equals the concentration of OH- ions in the water. D) the concentration of H+ ions in the water is 7 times the concentration of OH- ions in the water. E) The concentration of OH- ions in the water is 7 times the concentration of H+ ions in the water.

C

Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon? A) the change in density when it condenses to form a liquid or solid B) reactions with other atmospheric compounds C) the release of heat by the formation of hydrogen bonds D) the release of heat by the breaking of hydrogen bonds E) the high surface tension of water

C

Water is able to form hydrogen bonds because A) oxygen has a valence of 2. B) the water molecule is shaped like a tetrahedron. C) the bonds that hold together the atoms in a water molecule are polar covalent bonds. D) the oxygen atom in a water molecule has a weak positive charge. E) each of the hydrogen atoms in a water molecule is weakly negative in charge.

C

Waters high specific heat is mainly a consequence of the A) small size of the water molecules. B) high specific heat of oxygen and hydrogen atoms. C) absorption and release of heat when hydrogen bonds break and form. D) fact that water is a poor heat conductor. E) inability of water to dissipate heat into dry air.

C

When an ionic compound such as sodium chloride (NaCl) is placed in water the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of particles

C

You have a freshly-prepared 0.1M solution of glucose in water. Each liter of this solution contains how many glucose molecules? A) 6.02 × 1023 B) 3.01 × 1023 C) 6.02 × 1024 D) 12.04 × 1023 E) 6.02 × 1022

C

One liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 L of a solution of pH 6? A) 4 times more B) 400 times more C) 4,000 times more D) 10,000 times more E) 100,000 times more

D

Research indicates that acid precipitation can damage living organisms by A) buffering aquatic systems such as lakes and streams. B) decreasing the H+ concentration of lakes and streams. C) increasing the OH- concentration of lakes and streams. D) washing away certain mineral ions that help buffer soil solution and are essential nutrients for plant growth. E) both B and C

D

The nutritional information on a cereal box shows that one serving of a dry cereal has 200 kilocalories. If one were to burn one serving of the cereal, the amount of heat given off would be sufficient to raise the temperature of 20 kg of water how many degrees Celsius? A) 0.2°C B) 1.0°C C) 2.0°C D) 10.0°C E) 20.0°C

D

What gives rise to the cohesiveness of water molecules? A) hydrophobic interactions B) nonpolar covalent bonds C) ionic bonds D) hydrogen bonds E) both A and C

D

What is the pH of a solution with a hydrogen ion [H +] concentration of 10-8 M? A) pH 2 B) pH 4 C) pH 6 D) pH 8 E) pH 10

D

Which of the following statements correctly defines a kilocalorie? A) the amount of heat required to raise the temperature of 1 g of water by 1°F B) the amount of heat required to raise the temperature of 1 g of water by 1°C C) the amount of heat required to raise the temperature of 1 kg of water by 1°F D) the amount of heat required to raise the temperature of 1 kg of water by 1°C E) the amount of heat required to raise the temperature of 1,000 g of water by 1°F

D

Which of the following statements is completely correct? A) H2CO3 is a weak acid, and NaOH is a weak base (alkali). B) H2CO3 is a strong acid, and NaOH is a strong base (alkali). C) NH3 is a weak base (alkali), and H2CO3 is a strong acid. D) NH3 is a weak base (alkali), and HCl is a strong acid. E) NH3 is a strong base (alkali), and HCl is a weak acid.

D

Which of the following statements is true about buffer solutions? A) They maintain a constant pH when bases are added to them but not when acids are added to them. B) They maintain a constant pH when acids are added to them but not when bases are added to them. C) They maintain a constant pH of exactly 7 in all living cells and biological fluids. D) They maintain a relatively constant pH when either acids or bases are added to them. E) They are found only in living systems and biological fluids.

D

Which type of bond must be broken for water to vaporize? A) ionic bonds B) nonpolar covalent bonds C) polar covalent bonds D) hydrogen bonds E) covalent bonds

D

Why does ice float in liquid water? A) The liquid water molecules have more kinetic energy and thus support the ice. B) The ionic bonds between the molecules in ice prevent the ice from sinking. C) Ice always has air bubbles that keep it afloat. D) Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water. E) The crystalline lattice of ice causes it to be denser than liquid water.

D

A 100 mL beaker contains 10 mL of NaOH solution at pH = 13. A technician carefully pours into the beaker, 10 mL of HCl at pH = 1. Which of the following statements correctly describes the results of this mixing? A) The concentration of Na+ ion rises. B) The concentration of Cl- ion falls. C) The concentration of undissociated H2O molecules remains unchanged. D) The pH of the beakers contents rises. E) The pH of the beakers contents falls.

E

Buffers are substances that help resist shifts in pH by A) releasing H+ in acidic solutions. B) donating H+ to a solution when they have been depleted. C) releasing OH- in basic solutions. D) accepting H+ when the are in excess. E) Both B and D are correct.

E

Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that A) solution Y has no free hydrogen ions (H+). B) the concentration of hydrogen ions in solution X is 30 times as great as the concentration of hydrogen ions in solution Y. C) the concentration of hydrogen ions in solution Y is 1,000 times as great as the concentration of hydrogen ions in solution X. D) the concentration of hydrogen ions in solution X is 3 times as great as the concentration of hydrogen ions in solution Y. E) None of the other answer choices correctly describes these solutions.

E

How many molecules of glucose (C6H2O6 molecular mass =180 daltons) would be present in one mole of glucose? A) 24 B) 342 C) 23 × 1014 D) 180 × 1014 E) 6.02 × 1023

E

How many molecules of glycerol (C3H8O3) would be present in 1 L of a 1 M glycerol solution? A) 1 B) 14 C) 92 D) 1 × 107 E) 6.02 × 1023

E

If the pH of a solution is decreased from 9 to 8, it means that the A) concentration of H+ has decreased to one-tenth (1/10) what it was at pH 9. B) concentration of H+ has increased 10-fold (10X) compared to what it was at pH 9. C) concentration of OH- has increased 10-fold (10X) compared to what it was at pH 9. D) concentration of OH- has decreased to one-tenth (1/10) what it was at pH 9. E) Both B and D are correct.

E

One mole (mol) of a substance is A) 6.02 × 1023 molecules of the substance. B) 1 g of the substance dissolved in 1 L of solution. C) the largest amount of the substance that can be dissolved in 1 L of solution. D) the molecular mass of the substance expressed in grams. E) A and D only

E

The molecular mass of glucose is 180 g. Which of the following procedures should you carry out to make a 1 M solution of glucose? A) Dissolve 1 g of glucose in 1 L of water. B) Dissolve 180 g of glucose in 1 L of water. C) Dissolve 180 g of glucose in 100 g of water. D) Dissolve 180 mg (milligrams) of glucose in 1 L of water. E) Dissolve 180 g of glucose in water, and then add more water until the total volume of the solution is 1 L.

E

Which of the following ionizes completely in solution and is considered to be a strong base (alkali)? A) NaCl B) HCl C) NH3 D) H2CO3 E) NaOH

E

Which of the following solutions has the greatest concentration of hydroxyl ions [OH-]? A) lemon juice at pH 2 B) vinegar at pH 3 C) tomato juice at pH 4 D) urine at pH 6 E) seawater at pH 8

E

Equal volumes of vinegar from a freshly-opened bottle are added to each of the following solutions. After complete mixing, which of the mixtures will have the highest pH? A) 100 mL of pure water B) 100 mL of freshly-brewed coffee C) 100 mL of household cleanser containing 0.5M ammonia D) 100 mL of freshly-squeezed orange juice E) 100 mL of tomato juice

c

We can be sure that a mole of table sugar and a mole of vitamin C are equal in their A) mass in daltons. B) mass in grams. C) number of molecules. D) number of atoms. E) volume.

c

Which of the following is a hydrophobic material? A) paper B) table salt C) wax D) sugar E) pasta

c