The loss of water from a plant by transpiration cools the leaf. Movement of water in transpiration requires both adhesion to the conducting walls and wood fibers of the plant and cohesion of the molecules to each other. A scientist wanted to increase the rate of transpiration of a crop species to extend its range into warmer climates. The scientist substituted a nonpolar solution with an atomic mass similar to that of water for hydrating the plants. What do you expect the scientist's data will indicate from this experiment?
Transpiration rates will fall to zero as nonpolar compounds do not have the properties necessary for adhesion and cohesion.
Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O ↔ H2CO3. Carbonic acid (H2CO3) is a weak acid. If CO2 is bubbled into a beaker containing pure, freshly distilled water, which of the following graphs correctly describes the results?
line going down
If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, then the concentration of H+ ions ________.
is 10 times higher in the cytoplasm than in the mitochondrial matrix
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
Increased atmospheric CO2 concentrations might have what effect on seawater?
Seawater will become more acidic, and carbonate concentrations will decrease.
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 graphs describes the relationship between [H3O+] and pH?
line going down
As the [H3O+] of the solution decreases, the [OH-] ________.
increases and thus pH increases
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
Assume that acid rain has lowered the pH of a particular lake to pH 5.0. What is the hydroxide ion concentration of this lake?
1 × 10-9 mol of hydroxide ions per liter of lake water
Carbon dioxide in the atmosphere dissolves with the raindrops. The pH of raindrops is ________.
slightly acidic
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+). (See figure.)
If the pH of blood drops, one would expect ________.
the HCO3- to act as a base and remove excess H+ by the formation of H2CO3
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.
What is the hydroxyl ion (OH-) concentration of a solution of pH 8?
10-6 M
What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10-10 M?
pH 4
A solution contains 0.0000001 (10-7) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution?
neutral
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.
Which of the following is considered to be a strong base (alkali)?
NaOH → Na+ + OH-
Consider the following reaction at equilibrium: CO2 + H2O ⇌ H2CO3. What would be the effect of adding additional H2O?
It would drive the equilibrium dynamics to the right.
A solution with a pH of 2 has how many more protons in it than a solution with a pH of 4?
100 times more
Rank, from low to high, the pH of blood, stomach acid, and urine.
stomach acid, urine, blood
Identical heat lamps are arranged to shine on two identical containers, one containing water and one methanol (wood alcohol), so that each liquid absorbs the same amount of energy minute by minute. The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. Which of the following graphs correctly describes what will happen to the temperature of the water and the methanol?
dash line on top; splitting away from each other
How much of 0.5 M glucose (molecular mass 180) is needed to provide 100 mg of glucose?
1.11 mL
How many grams of the compound in the figure are required to make 1 liter of a 0.5 M solution? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)
30
Use the following figure to answer the question.
Two moles of the compound in the figure would weigh how many
grams? (Note: The atomic masses, in daltons, are approximately 12 for
carbon, 1 for hydrogen, and 16 for oxygen.)
120
Use the following figure to answer the question.
Based on your knowledge of the polarity of water molecules, the
solute molecule depicted is most likely ________.
positively charged
How does 0.5 M sucrose (molecular mass 342) solution compare to 0.5 M glucose (molecular mass 180) solution?
Both have 3.01 × 1023 molecules.
You have a freshly prepared 0.1 M sucrose (molecular mass 342) solution, which means ________.
6.02 × 1022 of sucrose molecules or 34.2 g of sucrose is present in the solution
The molar mass of glucose is 180 grams per mole (g/mol). Which of the following procedures should you carry out to make a 1 M solution of glucose? In 0.8 liter (L) of water, dissolve ________.
180 g of glucose, and then add more water until the total volume of the solution is 1 L
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 solute particles (molecules or ions)?
1 liter of 1.0 M NaCl
One mole (mol) of glucose (molecular mass = 180 daltons) is ________.
180 grams of glucose
Melting of ice and thus reduced feeding opportunities for polar bears is occurring because of the ________.
increase in CO2 and other greenhouse gases in the atmosphere
Why is a steam burn more severe than a hot water burn?
Steam contains more energy than water.
Hydrophobic substances such as vegetable oil are ________.
nonpolar substances that repel water molecules
Why does ice float in liquid water?
Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.
A dietary Calorie equals 1 kilocalorie. One kilocalorie equals ________.
1000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°C
Low humidity in the atmosphere on a hot day ________.
helps in cooling because water evaporates from the skin faster
Thermal energy of the water in a bathtub is ________ than in a freshly brewed coffee pot because of its ________.
higher; greater volume
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.
Water has many exceptional and useful properties. Which is the rarest property among compounds?
Solid water is less dense than liquid water.
To act as an effective coolant in a car's radiator, a substance has to have the capacity to absorb a great deal of heat. You have a reference book with tables listing the physical properties of many liquids. In choosing a coolant for your car, which table would you check first?
specific heat
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.
Which of the following can be attributed to water's high specific heat?
A lake heats up more slowly than the air around it.
Liquid water ________.
has a heat of vaporization higher than that of most other substances
Cohesion, surface tension, and adhesion are the properties of water molecules that ________.
are a result of hydrogen bonding
Water molecules can form hydrogen bonds with ________.
compounds that have polar covalent bonds
Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S will ________.
not form hydrogen bonds with each other
The partial negative charge in a molecule of water occurs because ________.
the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus
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
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by ________.
polar covalent bonds