Biology Chapter 3
Urine, at pH 6, contains __________ H+ as household bleach, at pH 13. 10,000,000 times as much 1/10,000,000 times as much 7 times as much 1/7 times as much half as much
10,000,000 times as much
What is the hydroxide ion concentration of the lake described in question 3?
10−10M
If the molecular mass of a carbon atom is 12, the mass of a hydrogen atom is 1, and the mass of an oxygen atom is 16 daltons, how many molecules does one mole of table sugar (sucrose; C12H22O11) contain? 6.02 x 1023 45 6.02 x 1023/342 342 (6.02 x 1023)(342)
6.02 x 10^23
The ability of water molecules to form hydrogen bonds with other water molecules and water's ability to dissolve substances that have charges or partial charges are __________.
both caused by water's partial charges
Nonpolar molecules that cluster away from water molecules are called __________ molecules.
hydrophobic
What are nonpolar molecules that cluster away from water molecules called? ionic hydrophilic hydrophobic None of the listed responses is correct.
hydrophobic
A solution at pH 10 contains __________ than the same amount of solution at pH 8. 100 times less H+ 100 times more H+ 2 times more H+ 2 times less H+ 4 times less H+
100 times less H+
A solution at pH 6 contains __________ than the same amount of solution at pH 8. 2 times more H+ 4 times more H+ 100 times more H+ 4 times less H+
100 times more H+ (Each pH unit change represents a tenfold difference in the hydrogen ion concentration; thus 10 × 10 = 100.)
A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what would be the approximate increase in the temperature of the water? (NOTE: A liter of cold water weighs about 1 kg.)
10°C
Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?
10−4M
Select the statement that best describes a buffer A buffer causes acidic solutions to become alkaline, and alkaline solutions to become acidic. A buffer resists change in pH by accepting hydrogen ions when acids are added to the solution and donating hydrogen ions when bases are added. Buffered solutions are always neutral, with a pH of 7. A buffer stabilizes the pH of a solution by preventing acids or bases from dissociating. A buffer prevents the pH of a solution from changing when an acid or base is added.
A buffer resists change in pH by accepting hydrogen ions when acids are added to the solution and donating hydrogen ions when bases are added.
What do cohesion, surface tension, and adhesion have in common with reference to water? All are produced by covalent bonding. All have to do with ionic interactions. All are results of the structure of the hydrogen atom. All are properties related to hydrogen bonding.
All are properties related to hydrogen bonding
The absorption of human-generated CO2 by the oceans __________. increases the oceanic concentration of carbonic acid increases the oceans' acidity and lowers pH reduces the carbonate ion concentration in the oceans and threatens calcifying organisms in marine ecosystems increases the hydrogen ion concentration in the oceans but decreases the carbonate ion concentration and threatens the livability of the oceans for calcifying organisms All of the listed responses are correct
All of the listed responses are correct
A substance that minimizes changes in the concentration of H+ and OH- in a solution is a __________. hydrophobic molecule strong acid NaCl Buffer
Buffer
The phenomenon responsible for maintaining the upward movement of water through vessels in a tree is __________. cohesion specific heat surface tension hydration shells
Cohesion
In agricultural areas, farmers pay close attention to the weather forecast. Right before a predicted overnight freeze, farmers spray water on crops to protect the plants. Use the properties of water to explain how this method works. Be sure to mention why hydrogen bonds are responsible for this phenomenon.
Due to intermolecular hydrogen bonds, water has a high specific heat (the amount of heat required to increase the temperature of water by 1°C). When water is heated, much of the heat is absorbed in breaking hydrogen bonds before the water molecules increase their motion and the temperature increases. Conversely, when water is cooled, many H bonds are formed, which releases a significant amount of heat. This release of heat can provide some protection against freezing of the plants' leaves, thus protecting the cells from damage.
Which of the following accurately relates the emergent properties of water to the effects of global warming in the Arctic? Ice floats because it is less dense than liquid water; floating ice insulates water below and provides a habitat for some species. The significant increase in Arctic air temperature over the past 50 years is causing a reduction in sea ice, compromising these beneficial effects of sea ice. Although a significant increase of air temperature has occurred in the Arctic over the past 50 years, the specific heat of water has thus far buffered against any significant increases in the Arctic ocean temperatures. Although it is feared that sea ice around Alaska and northern Canada may be greatly reduced by atmospheric warming, the high specific heat of water has so far buffered these sea ice communities from significant impacts. An increase in water temperature due to global warming will cause the sea ice formed in the Arctic to be denser and less buoyant.
Ice floats because it is less dense than liquid water; floating ice insulates water below and provides a habitat for some species. The significant increase in Arctic air temperature over the past 50 years is causing a reduction in sea ice, compromising these beneficial effects of sea ice.
An acid is __________. a material that resists changes in the pH of a solution any compound with a pH any compound that accepts hydrogen ions a compound that donates hydrogen ions to a solution
a compound that donates hydrogen ions to a solution
Water has __________ than other liquids such as ethanol , reflecting its capacity to absorb large amounts of heat. a higher boiling point a lower capacity for forming hydrogen bonds a lower heat of vaporization lower specific heat
a higher boiling point
Water molecules have __________ than molecules of similar size, such as ammonia and methane, reflecting its capacity to absorb large amounts of heat. a higher boiling point lower specific heat a lower melting point a lower capacity for forming hydrogen bonds less surface tension
a higher boiling point
Sodas typically contain sugar, flavorings, coloring agents, and carbon dioxide dissolved in water. The best term to describe this mixture would be _____. solvent aqueous solution suspension solute aqueous solvent
aqueous solution
Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _____. bility to form colloids cohesion high specific heat buffering activity lower density in the solid phase
high specific heat
How does the polarity of water contribute to its ability to dissolve so many substances? Water's polarity allows it to form covalent bonds with many substances Because it is polar, water's negatively charged oxygen atoms and positively charged hydrogen atoms are attracted to positively and negatively charged ions and molecules. Because it is polar, water forms ionic bonds with the ions in substances such as NaCl (salt). Natural water has a pH of approximately 5.6, which is slightly acidic. Acids can dissolve more substances than bases can.
Because it is polar, water's negatively charged oxygen atoms and positively charged hydrogen atoms are attracted to positively and negatively charged ions and molecules.
What do climate change (see Concept 1.1 and Concept 3.2) and ocean acidification have in common?
Both global warming and ocean acidification are caused by increasing levels of carbon dioxide in the atmosphere, the result of burning fossil fuels.
Which of the following dissociations is that of an acid? NaOH → Na+ + OH- HF → H+ + F- H2O → H+ + OH- NH3 + H+ → NH4+
HF → H+ + F- (Hydrofluoric acid (HF) dissociates into a hydrogen ion and a fluoride ion)
Which of the following occurs because molecules of water are farther apart in ice than in liquid water? Ice vaporizes before liquid water does. Ice expands when it melts. Ice is denser than liquid water. Ice floats.
Ice floats.
You can fill a glass of water to just slightly above the rim without it spilling over the glass. What property of water best explains this phenomenon
Surface tension
Imagine that organisms consisted of 70-95% alcohol instead of 70-95% water. Alcohol's specific heat is about half that of water. How would living things be different? Organisms would be able to live in a much wider range of temperatures. Living organisms would have to be much smaller. Systems for temperature regulation would have to be much more efficient. Warm-blooded organisms would require less insulation such as fur or feathers.
Systems for temperature regulation would have to be much more efficient.
A substance that reduces the hydrogen ion concentration of a solution is __________ a base an acid a buffer neutral
a base
An acid is __________.
a compound that donates hydrogen ions to a solution
A compound that donates hydrogen ions to a solution is __________. an acid a base a buffer neutral
an acid
The phenomenon responsible for maintaining the upward movement of water through a vessel is __________.
cohesion
Adding acid tends to __________ of a solution. decrease the hydrogen ion concentration and raise the pH increase the hydrogen ion concentration and lower the pH increase the hydrogen ion concentration and raise the pH decrease the hydrogen ion concentration and lower the pH
increase the hydrogen ion concentration and lower the pH (Because pH is a negative log, its value is inversely proportional to the hydrogen ion concentration.)
The specific heat of a substance is __________. the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C 1 calorie 1 kilocalorie always the same as the mass of the liquid equivalent to the heat of vaporization
the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C
The partial charges on a water molecule occur because of __________. the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule the achievement of a stable configuration by one atom of a bond but not by the other partner covalent bonding widespread ionization the high electronegativity of hydrogen
the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule
Sweating has a cooling effect because of water's high __________. buffering capacity surface tension specific heat heat of vaporization
heat of vaporization
Which of the following is a hydrophobic material?
wax
Adding a base tends to __________ of a solution.
lower the hydrogen ion concentration and increase the pH
Cells are surrounded by water, and cells themselves consist of about 70-95% water. Which of the following occurs as a result? A variety of nutrient molecules is readily available as dissolved solutes. Waste products produced by cell metabolism can be easily removed. The temperature of living things tends to change relatively slowly. All of the listed responses are correct.
-Waste products produced by cell metabolism can be easily removed -A variety of nutrient molecules is readily available as dissolved solutes. -The temperature of living things tends to change relatively slowly.
A mole of ethyl alcohol weighs 46 g. How many grams of ethyl alcohol are needed to produce 1 L of a 2-millimolar (2 mM) solution? A mole of ethyl alcohol weighs 46 g. How many grams of ethyl alcohol are needed to produce 1 L of a 2-millimolar (2 mM) solution?
0.092 g
Why are cell membranes composed primarily of hydrophobic molecules? Cell membranes must be composed of polar molecules in order to interact with the aqueous solutions inside of cells. In order to maintain a proper pH, cell membranes must be hydrophobic. Cell membranes must be hydrophobic in order to allow polar and charged molecules to enter and leave the cell. In order to perform their function of separating the aqueous solutions outside of cells from the aqueous solutions inside of cells, cell membranes cannot be soluble in water.
In order to perform their function of separating the aqueous solutions outside of cells from the aqueous solutions inside of cells, cell membranes cannot be soluble in water.
Why is the increasing amount of carbon dioxide being taken up by the oceans a cause for concern? More carbon dioxide causes an increase in carbonic acid (H2CO3), which leads to a decrease in the concentration of carbonate ion (CO32-). There is no cause for concern. Carbonic acid (H2CO3) is an excellent buffer and will help keep the pH of seawater constant. More carbon dioxide causes an increase in carbonic acid (H2CO3), which leads to an increase in the concentration of carbonate ion (CO32-). The buffering action of carbonic acid (H2CO3) causes the pH of seawater to rise.
More carbon dioxide causes an increase in carbonic acid (H2CO3), which leads to a decrease in the concentration of carbonate ion (CO32-).
Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature? The absorption of heat by the breaking of hydrogen bonds. Water's change in density when it condenses. Water's ability to dissolve molecules in the air. The release of heat by the formation of hydrogen bonds. Water's high surface tension.
The absorption of heat by the breaking of hydrogen bonds.
If water were NOT a polar molecule, how would the effects of global warming differ from those currently observed or predicted to occur in the future? If water were nonpolar, the effects on global warming would be only slightly worse because there are other polar molecules that can moderate climate as water does. The effects would be drastically worse because the loss of the polar nature of water would greatly reduce its specific heat and its ability to moderate temperature. The effects would be worse because a loss of the polar molecular structure would lead to a greater amount of heat absorbed by water molecules and, thus, an increase in its specific heat. If water molecules were nonpolar, then water vapor would be less effective as a greenhouse gas and the effects of global warming would be less extreme.
The effects would be drastically worse because the loss of the polar nature of water would greatly reduce its specific heat and its ability to moderate temperature.v
Hydrophilic molecules __________. are charged molecules that are attracted to the partial charge of the water molecule are uncharged, nonionic substances that repel water are nonionic molecules that are attracted to the nonpolar portion of the water molecule are polar molecules that are attracted to the nonpolar portion of the water molecule never have a partial charge at one end of the molecule
are charged molecules that are attracted to the partial charge of the water molecule
Hydrophobic molecules __________. are uncharged, nonionic substances that seem to repel water are polar molecules that are attracted to the nonpolar portion of the water molecule are nonionic molecules that are attracted to the nonpolar portion of the water molecule are ionic molecules that are attracted to the polar portion of the water molecule always have a partial charge at one end of the molecule
are uncharged, nonionic substances that seem to repel water
The ability of water molecules to form hydrogen bonds with other water molecules and water's ability to dissolve substances that have charges or partial charges are __________. both caused by water's two electron shells both caused by water's partial charges both caused by water's ability to form covalent bonds with hydrophobic substances due to water's partial charges and low molecular mass, respectively
both caused by water's partial charges (Two molecules of water are held together by a hydrogen bond formed between the slight positive charge of the hydrogen and the slight negative charge of the oxygen. Water is a very versatile solvent, a quality traced to the polarity of the water molecule.)
Water moves up a plant because of hydrogen bonds by a process called __________. cohesion and adhesion cohesion surface tension covalent interactions adhesion
cohesion and adhesion
Which action would involve the greatest transfer of heat? evaporating 1 g of water at 25°C cooling 10 g of water from 80°C to 40°C changing the temperature of 1 g of water from 10°C to 90°C condensing 5 g of steam to liquid water
condensing 5 g of steam to liquid water (This would release about 2,900 calories (580 calories/gram × 5 grams).
Sweating has a cooling effect because of water's high __________.
heat of vaporization
When ice forms, the __________ are farther apart than in liquid water, allowing the ice to form an organized crystal structure and float. hydrogen bonds ionic bonds adhesive interactions partial charges on the oxygen and hydrogen All of the listed responses are correct.
hydrogen bonds
A molecule that has all nonpolar covalent bonds would be __________. hydrophobic basic (alkaline) acidic hydrophilic
hydrophobic
The absorption of human-generated CO2 by the oceans __________ increases the hydrogen ion concentration in the oceans but decreases the carbonate ion concentration and threatens the livability of the oceans for organisms that produce calcium carbonate shells increases the oceanic concentration of carbonic acid increases the oceans' acidity and pH reduces the carbonate ion concentration in the oceans and threatens calcifying organisms in marine ecosystems
increases the hydrogen ion concentration in the oceans but decreases the carbonate ion concentration and threatens the livability of the oceans for organisms that produce calcium carbonate shells (The absorption of CO2 by the oceans causes an increase in the carbonic acid, and hydrogen ion concentration (lower pH). The extra hydrogen ions bind with the carbonate ion to form bicarbonate. This reduces the amount of carbonate ions available for calcification, the production of calcium carbonate (CaCO3) by many marine organisms, including reef-building corals and animals that build shells.)
An acid is a substance that _____. reduces the hydrogen ion concentration of a solution is a versatile solvent increases the hydrogen ion concentration of an aqueous solution contains hydrogen
increases the hydrogen ion concentration of an aqueous solution
The amount of energy that must be absorbed or lost to raise or lower the temperature of 1 g of liquid water by 1°C _____ is 1,000 joules is 1 kilocalorie is 1,000 kilocalories is 1 calorie is 1,000 calories depends on the initial temperature of the water sample
is 1 calorie
The tendency of water molecules to stay close to each other as a result of hydrogen bonding __________. provides the surface tension that allows small animals to move across a water surface helps to keep water moving through the vessels in a tree trunk is called cohesion is called cohesion, acts to moderate temperature, provides the surface tension that allows small animals to move across a water surface, and helps to keep water moving through the vessels in a tree trunk
is called cohesion, acts to moderate temperature, provides the surface tension that allows small animals to move across a water surface, and helps to keep water moving through the vessels in a tree trunk
When the pH of a solution shifts from 3 to 7, the hydrogen ion concentration has changed, and __________. it has decreased by 10,000 times it has increased by 4 times it has decreased by 4 times it has increased by 10,000 times It has not changed.
it has decreased by 10,000 times
Adding a base tends to __________ of a solution. lower the hydrogen ion concentration and lower the pH increase the hydrogen ion concentration and lower the pH lower the hydrogen ion concentration and increase the pH increase the hydrogen ion concentration and increase the pH
lower the hydrogen ion concentration and increase the pH
All of the following are hydrogen bonding properties except __________. nonpolar covalent bonding surface tension adhesion partial charges on the oxygen and hydrogen cohesion
nonpolar covalent bonding
We can be sure that a mole of table sugar and a mole of vitamin C are equal in their
number of molecules
Water is a very versatile solvent because water molecules are __________. polar hydrophobic nonpolar ionic
polar
The reason that coastal climates are more moderate than inland climates primarily water's high __________. surface tension specific heat adhesion heat of vaporization
specific heat
Sucrose has a molecular mass of 342 daltons. To make a 2-molar (2 M) solution of sucrose, __________. stir 684 g of sucrose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution up to 0.5 L stir 342 g of sucrose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution to 1 L stir 342 g of sucrose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution up to 0.5 L stir 684 g of sucrose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution up to 2 L
stir 342 g of sucrose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution up to 0.5 L
Buffers are __________. substances that minimize changes in the concentration of H+ and OH- in a solution substances that increase the concentration of H+ in a solution substances that decrease the concentration of H+ in a solution substances that increase the concentration of OH- in a solution substances that decrease the concentration of OH- in a solution
substances that minimize changes in the concentration of H+ and OH- in a solution
You can fill a glass of water to just slightly above the rim without the water spilling over the glass. What property of water best explains this phenomenon? adhesion surface tension its polarity None of the listed responses is correct.
surface tension
__________ is an emergent property of water that allows insects like the raft spider to walk on water. Surface tension Kinetic energy The heat of vaporization All of the listed responses are correct. Adhesion
surface tension
A glass of grapefruit juice, at pH 3, contains __________ H+ as a glass of tomato juice, at pH 4. one-tenth as much half as much twice as much ten times as much
ten times as much (The pH scale is a base-10 logarithmic scale. The change from any pH value to the next smaller value represents a tenfold increase in the hydrogen ion concentration.)
Water is a polar molecule. What does this statement mean? that the atoms in water have equal electronegativities that water is one of the many hydrophobic molecules that atoms in the molecule have partial charges as a result of unequal sharing of electrons in a covalent bond that water molecules are linear, like a pole
that atoms in the molecule have partial charges as a result of unequal sharing of electrons in a covalent bond
Adhesion is best described as __________.
the clinging of one substance to another substance
Adhesion is best described as which of the following? the clinging of one substance to another substance the process that contributes to the transport of water and dissolved nutrients in plants by causing water molecules to tug on other water molecules a property of water that helps moderate Earth's temperature the process by which a crystalline lattice forms
the clinging of one substance to another substance
The amount of heat required to convert 1 g of any substance from the liquid to the gaseous state is defined as __________. 1 calorie surface tension the heat of vaporization of that substance the specific heat of that substance
the heat of vaporization of that substance
Water is a polar molecule. This means that __________.
the opposite ends of the molecule have opposite electrical charges
In a group of water molecules, hydrogen bonds form between which of the following? two hydrogen atoms in different water molecules the oxygen atoms in different water molecules the oxygen atom in one water molecule and a hydrogen atom in another water molecule the hydrogen atoms in a single water molecule
the oxygen atom in one water molecule and a hydrogen atom in another water molecule
The amount of heat required to change the temperature of 1 g of any substance by 1°C is defined as __________. the heat of vaporization of that substance the specific heat of that substance 1 kilocalorie 1 calorie
the specific heat of that substance
The amount of heat required to change the temperature of 1 g of any substance by one °C is defined as __________. the specific heat of that substance 1 calorie the heat of vaporization of that substance 1 kilocalorie molecular cohesion
the specific heat of that substance
The partial charges on a water molecule occur because of __________. the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule the achievement of a stable configuration by one atom of a bond but not by the other partner widespread ionization covalent bonding
the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule ( Because oxygen is more electronegative than hydrogen, electrons of the polar bond spend more time closer to the oxygen atom, resulting in a slight negative charge on the oxygen atom and slight positive charges on the hydrogen atoms.)