Bio 1 chapter 3
Which of the following can be attributed to water's high specific heat? Answers: Oil and water do not mix well. A lake heats up more slowly than the air around it. Ice floats on water. Sugar dissolves in hot tea faster than in iced tea.
Selected Answer: A lake heats up more slowly than the air around it.
Which of the following effects can occur because of the high surface tension of water? Answers: Lakes cannot freeze solid in winter, despite low temperatures. A raft spider can walk across the surface of a small pond. Organisms can resist temperature changes, although they give off heat due to chemical reactions. Sweat can evaporate from the skin, helping to keep people from overheating.
Selected Answer: A raft spider can walk across the surface of a small pond.
Which of the following dissociates completely in solution and is considered to be a strong base (alkali)? Answers: HCl NH3 H2CO3 NaOH
Selected Answer: NaOH
Which of the following statements is true about buffer solutions? Answers: They maintain a constant pH when bases are added to them but not when acids are added to them. They maintain a constant pH when acids are added to them but not when bases are added to them. They fluctuate in pH when either acids or bases are added to them. They maintain a relatively constant pH when either acids or bases are added to them.
Selected Answer: They maintain a relatively constant pH when either acids or bases are added to them.
One of the buffers that contribute to pH stability in human blood is carbonic acid (H 2CO 3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO 3 -) and a hydrogen ion (H +), as noted below. h2co3 ---> hco3- + h+ If the pH of blood increases, one would expect _____. Answers: a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3- an increase in the concentration of H2CO3 and a decrease in the concentration of HCO3- a decrease in the concentration of HCO3- and an increase in the concentration of H+ an increase in the concentration of HCO3- and a decrease in the concentration of OH-
Selected Answer: a decrease in the concentration of H 2CO 3 and an increase in the concentration of HCO 3 -
The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. What is this attraction called? Answers: a covalent bond a hydrogen bond an ionic bond a van der Waals interaction
Selected Answer: a hydrogen bond
Water molecules can form hydrogen bonds with _____. Answers: compounds that have polar covalent bonds oils oxygen gas (O2) molecules chloride ions
Selected Answer: compounds that have polar covalent bonds
Which of the following solutions would require the addition of the greatest amount of base to bring the solution to neutral pH? Answers: gastric juice at pH 2 vinegar at pH 3 black coffee at pH 5 household bleach at pH 12
Selected Answer: gastric juice at pH 2
Which type of bond must be broken for water to vaporize? Answers: ionic bonds polar covalent bonds hydrogen bonds both polar covalent bonds and hydrogen bonds
Selected Answer: hydrogen bonds
Hydrophobic substances such as vegetable oil are _____. Answers: nonpolar substances that repel water molecules nonpolar substances that have an attraction for water molecules polar substances that repel water molecules polar substances that have an affinity for water
Selected Answer: nonpolar substances that repel water molecules
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by _____. Answers: hydrogen bonds nonpolar covalent bonds polar covalent bonds ionic bonds
Selected Answer: polar covalent bonds
Rank, from low to high, the pH of blood, stomach acid, and urine. Answers: blood, urine, and stomach acid stomach acid, blood, and urine urine, blood, stomach acid stomach acid, urine, blood
Selected Answer: stomach acid, urine, blood
One of the buffers that contribute to pH stability in human blood is carbonic acid (H 2CO 3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO 3 -) and a hydrogen ion (H +), as noted below. h2co3 ---> hco3- + h+ If the pH of blood drops, one would expect _____. Answers: a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3- the concentration of bicarbonate ions (HCO3-) to increase the HCO3- to act as a base and remove excess H+ by the formation of H2CO3 the HCO3- to act as an acid and remove excess H+ by the formation of H2CO3
Selected Answer: the HCO 3 - to act as a base and remove excess H + by the formation of H 2CO 3
The partial negative charge in a molecule of water occurs because _____. Answers: the oxygen atom donates an electron to each of the hydrogen atoms the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms one of the hydrogen atoms donates an electron to the oxygen atom
Selected Answer: the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus
