Chapter 3 practice quiz
Hydrophobic substances such as vegetable oil are A) nonpolar substances that repel water molecules. B) polar substances that repel water molecules. C) nonpolar substances that have an attraction for water molecules. D) charged molecules that hydrogen-bond with water molecules. E) polar substances that have an affinity for water.
A
Which of the following effects is produced by the high surface tension of water? A) A water strider can walk across the surface of a small pond. B) Water can act as a solvent. C) The pH of water remains exactly neutral. D) Lakes don't freeze solid in winter, despite low temperatures. E) Organisms resist temperature changes, although they give off heat due to chemical reactions.
A
Which of the following solutions has the greatest concentration of hydrogen ions [H+]? A) gastric juice at pH 2 B) black coffee at pH 5 C) vinegar at pH 3 D) household bleach at pH 12 E) tomato juice at pH 4
A
One of the buffers that contribute to pH stability in human blood is carbonic acid H2CO3. Carbonic acid is a weak acid that when placed in an aqueous solution dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+ If the pH of the blood increases, one would expect A) a decrease in the concentration of HCO3 - and an increase in the concentration of H2O. B) a decrease in the concentration of H2CO3 and an increase in the concentration of H2O. C) an increase in the concentration of H2CO3 and a decrease in the concentration of H2O. D) an increase in the concentration of HCO3 - and a decrease in the concentration of H2O. E) a decrease in the concentration of HCO3 - and an increase in the concentration of both H2CO3 and H2O.
B
What is the pH of a solution with a hydrogen ion [H+] concentration of 10-8 M? A) pH 6 B) pH 8 C) pH 10 D) pH 2 E) pH 4
B
Pure, freshly-distilled water has a pH of 7. This means that A) The concentration of OH- ions in the water is 7 times the concentration of 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) there are no H+ ions in the water.
C
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) an ionic bond B) a hydrophobic bond C) a hydrogen bond D) a covalent bond E) a hydrophilic bond
C
Water's high specific heat is mainly a consequence of the A) high specific heat of oxygen and hydrogen atoms. B) small size of the water molecules. 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
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°C D) the amount of heat required to raise the temperature of 1,000 g of water by 1°F E) the amount of heat required to raise the temperature of 1 kg of water by 1°F
C
Which of the following takes place as an ice cube cools a drink? A) A calorie of heat energy is transferred from the ice to the water of the drink. B) Evaporation of the water in the drink increases. C) Kinetic energy in the drink decreases. D) The specific heat of the water in the drink decreases. E) Molecular collisions in the drink increase.
C
Why does ice float in liquid water? A) The ionic bonds between the molecules in ice prevent the ice from sinking. B) The liquid water molecules have more kinetic energy and thus support the ice. C) The crystalline lattice of ice causes it to be denser than liquid water. D) Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water. E) Ice always has air bubbles that keep it afloat.
D
Buffers are substances that help resist shifts in pH by A) releasing OH- in basic solutions. B) donating H+ to a solution when they have been depleted. C) releasing H+ in acidic solutions. D) accepting H+ when the are in excess. E) Both B and D are correct.
E