Biology Chapter 3
Assume that acid rain has lowered the pH of a particular lake to pH 4.0. What is the hydroxide ion concentration of this lake?
1 × 10-10 mol of hydroxide ions per liter of lake water
One liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 liter of a solution of pH 6?
10,000 times more
What is the hydrogen ion (H+) concentration of a solution of pH 8?
10-8 M
A solution with a pH of 5 has how many more protons in it than a solution with a pH of 7?
100 times
Which of the following can be attributed to water's high specific heat?
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?
A raft spider can walk across the surface of a small pond.
If the pH of a solution is decreased from 9 to 8, it means that the concentration of _____.
H+ has increased tenfold (10X) compared to what it was at pH 9
A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance?
It is a strong acid that dissociates completely in water.
You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen.
NaCl crystals will dissolve readily in water but will not dissolve in methanol.
Which of the following dissociates completely in solution and is considered to be a strong base (alkali)? HCl NH3 NaOH H2CO3
NaOH
Increased atmospheric CO2 concentrations might have what effect on seawater?
Seawater will become more acidic, and carbonate concentrations will decrease.
Water has many exceptional and useful properties. Which is the rarest property among compounds?
Solid water is less dense than liquid water.
Why does ice float in liquid water?
Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.
The cities of Portland, Oregon, and Minneapolis, Minnesota, are at about the same latitude, but Minneapolis has much hotter summers and much colder winters than Portland. Why?
The ocean near Portland moderates the temperature.
A beaker contains 100 milliliters (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 result of this mixing?
The pH of the beaker's contents will decrease
Which of the following statements is true about buffer solutions?
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 (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+), as noted below. H2CO3<->HCO3(-)+H(+) If the pH of blood increases, one would expect _____.
a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-
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?
a hydrogen bond
How would acidification of seawater affect marine organisms? Acidification of seawater would _____.
decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals
A strong acid like HCl _____.
dissociates completely in an aqueous solution
Which of the following solutions would require the addition of the greatest amount of base to bring the solution to neutral pH?
gastric juice at pH 2
Which of the following is a property of liquid water? Liquid water _____.
has a heat of vaporization that is higher than that for most other substances
Which type of bond must be broken for water to vaporize?
hydrogen bonds
A solution contains 0.0000001 (10-7) moles of hydroxyl ions [OH-] per liter. Which of the following best describes this solution?
neutral
Hydrophobic substances such as vegetable oil are _____.
nonpolar substances that repel water molecules
What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10-12 M?
pH 2
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by _____.
polar covalent bonds
Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely https://cascadia.instructure.com/assessment_questions/119816887/files/70711020/download?verifier=FkG4Q53qveU2676YBXXJHDrJDSXuAfQsfO8nhOwL
positively charged
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+), as noted below. H2CO3<->HCO3(-)+H(+) If the pH of blood drops, one would expect
the HCO3 to act as base and remove excess H(+) by the formation of H2CO3
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 _____.
the concentration of hydrogen ions in solution X is 1000 times as great as the concentration of hydrogen ions in solution Y