Preview Extract
Chapter 16 Mixtures
16.1 Most Materials are Mixtures
1) What is the difference between a compound and a mixture?
A) A mixture can be physically separated into its components; a compound cannot be physically
separated into its components.
B) A compound can be physically separated into its components; a mixture cannot be physically
separated into its components.
C) A compound is just a mixture of elements.
D) The components of a mixture do not have the same properties individually as they do when
mixed.
E) The components of a compound have the same properties individually as they do when
mixed.
Answer: A
2) Which of the following is a mixture?
A) air
B) gold
C) salt
D) iron
E) helium
Answer: A
3) The following image represents which kind of matter?
A) a mixture
B) a compound
C) an element
D) none of the above
E) all of the above
Answer: A
4) The following image represents which kind of matter?
A) a compound
B) a mixture
C) an element
D) none of the above
E) all of the above
Answer: A
5) A combination of two or more substances in which they no longer retain their chemical
properties is called a(n) ________.
A) mixture
B) compound
C) heterogeneous mixture
D) periodic trend
E) suspension
Answer: B
6) Each circle represents an atom. Which of the following boxes contains an element? A
compound? A mixture?
A) element: A, C; compound: A, B, C; mixture: A, B
B) element: C; compound: A, B; mixture: B
C) element: A, C; compound: A, B; mixture: A
D) element: A, C; compound: A, B; mixture: A, B
Answer: C
7) What is the difference between a compound and a mixture?
A) They both consist of atoms from different elements.
B) The way in which their atoms are bonded together.
C) One is a solid and the other is a liquid.
D) The components of a mixture are not chemically bonded together.
Answer: D
8) How might you separate a mixture of sand and salt?
A) with tweezers and a magnifying glass
B) just add water
C) heat the mixture until one of the components melts
D) Two of the above answers are reasonable.
Answer: D
9) Mixtures can be separated into their components by taking advantage of differences in the
chemical properties of the components. Why might this separation method be less convenient
than taking advantage of differences in the physical properties of the components?
A) A chemical property involves a chemical change so that you no longer have what you had.
B) Chemical properties are not as apparent as are physical properties.
C) The chemical properties of the components of a mixture are too similar to each other.
D) The chemical properties of the components of a mixture are too different from each other.
Answer: A
10) Why can't the elements of a compound be separated from one another by physical means?
A) They are too homogeneous when found within a compound.
B) Their atoms are too tightly bound to one another.
C) Elements found within a compound tend to be inert.
D) Elements tend not to be soluble in water.
Answer: B
11) Half-frozen fruit punch is always sweeter than the same fruit punch completely melted
because
A) the sugar sinks to the bottom.
B) crystallization is a purifying process.
C) the half-frozen fruit punch is warmer.
D) sugar molecules are less soluble in a half-frozen solution.
Answer: B
12) Many dry cereals are fortified with iron, which is added to the cereal in the form of small
iron particles. How might these particles be separated from the cereal?
A) add water and the iron particles will float to the top
B) blend the cereal to a fine consistency and pass through a filter
C) collect the iron filings with a magnet
D) heat the cereal so that the iron particles melt and thereby coalesce
Answer: C
16.2 The Chemist's Classification of Matter
1) Which of the following would be considered a heterogeneous mixture?
A) salad dressing
B) water
C) milk
D) vegetable oil
E) vinegar
Answer: A
2) Which of the following is a pure substance?
A) baking soda
B) salt water
C) cooking oil
D) duct tape
E) orange juice
Answer: A
3) How would you classify the following material?
swimming pool water
A) homogeneous mixture
B) heterogeneous mixture
C) a pure element
D) a pure compound
E) depends on how many children have been in it
Answer: A
4) Which of the following would be considered a homogeneous mixture?
A) wine
B) hydrogen cyanide
C) rusty iron
D) pretzel
E) sugar
Answer: A
5) If you filter sea water to remove all of the particles you would be left with a clear ________.
A) homogeneous mixture called a solution
B) homogeneous mixture called a suspension
C) heterogeneous mixture called a solution
D) heterogeneous mixture called a suspension
E) pure liquid
Answer: A
6) When blue food coloring is stirred into water, the result is a ________.
A) homogeneous mixture called a solution
B) homogeneous mixture called a suspension
C) heterogeneous mixture called a solution
D) heterogeneous mixture called a suspension
E) pure liquid
Answer: A
7) How would you classify the following material?
milk
A) a suspension
B) a heterogeneous mixture
C) a solution
D) an element
E) a compound
Answer: A
8) How would you classify the following material?
coffee (black)
A) a suspension
B) a heterogeneous mixture
C) a solution
D) an element
E) a compound
Answer: C
9) How would you classify the following material?
coffee (with milk)
A) a suspension
B) a heterogeneous mixture
C) a solution
D) an element
E) a compound
Answer: A
10) How would you classify the following material?
a cappuccino (with foam)
A) a suspension
B) a heterogeneous mixture
C) a solution
D) an element
E) a compound
Answer: B
11) A sample of water that is 99.9999 percent pure contains 0.0001 percent impurities. Consider
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from Chapter 1 that a glass of water contains on the order of a trillion trillion (1 × 10 )
molecules. If 0.0001 percent of these molecules were the molecules of some impurity, about how
many impurity molecules would this be?
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A) 1000 (one thousand: 1 × 10 )
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B) 1,000,000 (one million: 1 × 10 )
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C) 1,000,000,000 (one billion: 1 × 10 )
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D) 1,000,000,000,000,000,000 (one million trillion: 1 × 10 )
Answer: D
12) What can be said about drinking water that is 99.9999 percent free of some poison, such as a
pesticide?
A) In each 10,000 parts of the contaminated water there is one part pesticide and 9999 parts pure
water.
B) In each 100,000 parts of the contaminated water there is one part pesticide and 99,999 parts
pure water.
C) The ratio of water molecules to pesticide molecules in the glass is so great that drinking the
water is not problematic.
D) The water is highly contaminated and surely not fit to drink.
Answer: C
13) Read carefully. Twice as much as one million trillion is two million trillion. One thousand
times as much is 1000 million trillion. One million times as much is 1,000,000 million trillion,
which is the same as one trillion trillion. Thus, one trillion trillion is a million times greater than
a million trillion. Got that? So how many more water molecules than impurity molecules are
there in a glass of water that is 99.9999 percent pure?
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A) 1000 (one thousand: 1 × 10 ) more water molecules than impurities molecules
B) 1,000,000 (one million: 1 × 106) more water molecules than impurities molecules
C) 1,000,000,000 (one billion: 1 × 109) more water molecules than impurities molecules
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D) 1,000,000,000,000,000,000 (one million trillion: 1 × 10 ) more water molecules than
impurities molecules
Answer: B
14) Someone argues that he or she doesn't drink tap water because it contains thousands of
molecules of some impurity in each glass. How would you respond in defense of the water's
purity, if it indeed does contain thousands of molecules of some impurity per glass?
A) Impurities aren't necessarily bad, in fact, they may be good for you.
B) The water contains water molecules and each water molecule is pure.
C) There's no defense. If the water contains impurities it should not be drunk.
D) Compared to the billions and billions of water molecules, a thousand molecules of something
else is practically nothing.
Answer: D
15) What do chicken noodle soup and garden soil have in common?
A) They are both examples of heterogeneous mixtures.
B) They both contain elements.
C) They are both examples of compounds.
D) nothing
Answer: A
16) Classify the following as element, compound, or mixture, and justify your classifications:
table salt, stainless steel, table sugar, aluminum, ice.
A) mixture; element; compound; element; element
B) compound; mixture; compound element; compound
C) mixture; compound; mixture; element; compound
D) compound; element; compound; element; compound
Answer: B
17) How does a suspension differ from a solution?
A) A suspension is a heterogeneous mixture whose components can be separated by simple
filtration. A solution is a homogeneous mixture which cannot be separated by simple filtration.
B) A suspension is a heterogeneous mixture consisting of different phases whereas a solution is a
homogeneous mixture consisting of a single phase.
C) Although a solution and suspension are both homogeneous mixtures, only the components of
a suspension will separate by spinning the mixture in a centrifuge.
D) The difference between a suspension and a solution can only be determined by chemical
means.
Answer: C
18) Which of the following boxes represents a suspension?
A) Only A represents a suspension.
B) Only B represents a suspension.
C) Only C represents a suspension.
D) Each of these could represent a submicroscopic portion of a suspension.
Answer: D
19) Is the air in your house a homogeneous or heterogeneous mixture?
A) homogeneous because it is mixed very well
B) heterogeneous because of the dust particles it contains
C) homogeneous because it is all at the same temperature
D) heterogeneous because it consists of different types of molecules
Answer: B
16.3 Solutions
1) Which of the following material phases cannot form a solution?
A) solids
B) liquids
C) gases
D) All of the above can form solutions.
E) None of the above can form solutions.
Answer: D
2) In a solution made from one teaspoon of sugar and one liter of water, which is the solute?
A) sugar
B) water
C) the teaspoon
D) both sugar and water
E) none of the above
Answer: A
3) In a solution of 77 percent nitrogen and 23 percent oxygen, which is the solvent?
A) nitrogen
B) oxygen
C) both
D) neither
E) Gases cannot form solutions.
Answer: A
4) A sample of steel is composed of 5 percent carbon and 95 percent iron. Which is the solvent?
A) iron
B) carbon
C) steel
D) Steel is not a solution, it is a mixture.
E) A solid cannot be a solvent.
Answer: A
5) Which of the following describes the term concentration?
A) It is what you are doing now to answer this question.
B) It is the amount of solute in a given amount of solution.
C) It is the amount of solvent in a given amount of solution.
D) It is the given amount of solution in a given container.
E) It is the given amount of solvent per amount of solute.
Answer: B
6) Which of the following statements describes a saturated solution?
A) a solution where the solvent cannot dissolve any more solute
B) a solution of salt water with salt at the bottom
C) a carbonated beverage with bubbles
D) all of the above
E) none of the above
Answer: D
7) Which of the following solutions is the most dilute?
A) one liter of water with 1 gram of sugar
B) one liter of water with 2 grams of sugar
C) one liter of water with 5 grams of sugar
D) one liter of water with 10 grams of sugar
E) They all have the same volume.
Answer: A
8) Which of the following solutions is the most concentrated?
A) one liter of water with 1 gram of sugar
B) one liter of water with 2 grams of sugar
C) one liter of water with 5 grams of sugar
D) one liter of water with 10 grams of sugar
E) They all have the same volume.
Answer: D
9) Which of the following solutions is the most dilute?
A) 0.1 liter of water with 1 gram of sugar
B) 0.2 liter of water with 2 grams of sugar
C) 0.5 liter of water with 5 grams of sugar
D) 1 liter of water with 10 grams of sugar
E) They all have the same concentration.
Answer: E
10) Which of the following solutions is the most concentrated?
A) 0.1 liter of water with 1 gram of sugar
B) 2 liters of water with 0.2 gram of sugar
C) 0.5 liter of water with 50 grams of sugar
D) 3 liters of water with 30 grams of sugar
E) They all have the same concentration.
Answer: C
11) Which has the most atoms?
A) a mole of gold
B) a mole of helium
C) a mole of lead
D) All of the above have the same number of atoms.
E) none of the above
Answer: D
12) What statement best describes a mole?
A) a little furry mammal that lives in the ground
B) a very small number chemists use to count atoms or molecules
C) the amount of molecules or atoms in 1 gram of something
D) It is a very large number chemists use to count atoms or molecules.
E) none of the above
Answer: D
13) What is molarity?
A) the number of moles of solute per liter of solution
B) the number of grams of solute per liter of solution
C) the number of moles of solute per liter of solvent
D) the number of liters of solute per mole of solution
E) none of the above
Answer: A
14) Which of the following best describes a two-molar sucrose solution?
A) one liter of solution that contains 2 moles of sucrose
B) one liter of solution that contains 2 moles of water
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C) one liter of solution that contains 6.02 × 10 molecules of sucrose
D) two liters of solution that contains 1 mole of sucrose
E) one mole of sucrose dissolved in 2 liters of solution
Answer: A
15) How many molecules of sucrose are in a 0.5 moles of sucrose?
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A) 3.01 × 10 molecules of sucrose
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B) 6.02 × 10 molecules of sucrose
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C) 12.04 × 10 molecules of sucrose
D) 0.5
E) 1 gram
Answer: A
16) How many molecules of sucrose are in 0.5 L of a 1 molar solution of sucrose?
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A) 3.01 × 10 molecules of sucrose
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B) 6.02 × 10 molecules of sucrose
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C) 12.04 × 10 molecules of sucrose
D) 0.5
E) 1 gram
Answer: A
17) How many molecules of sucrose are in 0.5 L of a 2 molar solution of sucrose?
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A) 3.01 × 10 molecules of sucrose
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B) 6.02 × 10 molecules of sucrose
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C) 12.04 × 10 molecules of sucrose
D) 0.5
E) 1 gram
Answer: B
18) If you need 10 moles of sucrose, how many liters of a 4.0 molar solution would you need?
A) 2.5 L
B) 0.25 L
C) 25 L
D) 10. L
E) none of the above
Answer: A
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19) If you need 3.01 × 10 molecules of sucrose, how many liters of a 4.00 molar solution
would you need?
A) 0.125 L
B) 0.250 L
C) 4.00 L
D) 1.00 L
E) none of the above
Answer: A
20) What is the molarity of 0.5 liters of a solution with five moles of sucrose in it?
A) 10 molar
B) 0.5 molar
C) 5 molar
D) 2.5 molar
E) 1 molar
Answer: A
21) Which of the following solutions is the most concentrated?
A) 0.5 L of a 3 molar solution
B) 3.0 L of a 0.5 molar solution
C) 2.0 L of a 1 molar solution
D) 0.5 L of a 1 molar solution
E) 2.0 L of a 2 molar solution
Answer: A
22) Many solvents expand to occupy greater volumes with increasing temperature. What
happens to the concentration of a solution made with such a solvent as its temperature is
increased?
A) Since concentration depends on how much mass is dissolved in a given volume, as the
volume increases, the concentration decreases.
B) The concentration of a solution increases as the solute fits into the new spaces between the
molecules.
C) Since it has a greater ability to dissolve more solute at a higher temperature, its concentration
has decreased.
D) Since it has a greater ability to dissolve more solute at a higher temperature, its concentration
has increased.
Answer: A
23) How many grams of sugar (sucrose) are there in 5 liters of sugar water that has a
concentration of 0.5 grams per liter of solution?
A) 50 g
B) 25 g
C) 2.5 g
D) 1.5 g
Answer: C
24) How many grams of sodium chloride are needed to make 15 L of a solution that has a
concentration of 3.0 g per liter of solution?
A) 30 g
B) 141 g
C) 5 g
D) 45 g
Answer: D
25) What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 liter of
solution?
A) 8 M
B) 4 M
C) 5 M
D) 2.5 M
Answer: B
26) A student is told to use 20.0 grams of sodium chloride to make an aqueous solution that has a
concentration of 10.0 grams of sodium chloride per liter of solution. Assuming that 20.0 grams
of sodium chloride has a volume of 7.5 milliliters, about how much water will she use in making
this solution?
A) 9.25 L
B) 9.5 L
C) 9.9925 L
D) 10 L
Answer: C
27) What is the sum of the atomic masses of all the atoms in sucrose, C12H22O11?
A) 342 amu
B) 182 amu
C) 270 amu
D) none of the above
Answer: A
28) How many moles of sugar, C12H22O11, are there in 200. grams?
A) 0.585 moles
B) 68,400 moles
C) 1.71 moles
D) 0.684 moles
Answer: A
29) How many moles of water are there in 100. grams of water?
A) 1800 moles
B) 100 moles
C) 0.018 moles
D) 5.55 moles
Answer: D
16.4 Solubility
1) How are intermolecular forces and solubility related?
A) Solubility depends on the solvent's ability to overcome the intermolecular forces in a solid.
B) Solubility depends on the solute's ability to overcome the intermolecular forces in the solvent.
C) Solubility is a measure of how strong a solvent's intermolecular forces are.
D) Solubility is a measure of how weak the intermolecular forces in the solute are.
E) none of the above
Answer: A
2) What happens when the molecule-to-molecule attractions in the solute are comparable to
those in the solvent?
A) The solute can have infinite solubility in the solvent.
B) The solute does not dissolve in the solvent.
C) The material has only limited solubility in the solvent.
D) The solution will become saturated.
E) none of the above
Answer: A
3) Which of the following might have the best solubility in water?
A) CH3OH
B) Cl2
C) O2
D) CH3CH3
E) none of the above
Answer: A
4) Which of the following might have the lowest solubility in water?
A) CH3OH
B) Cl2
C) O2
D) CH3CH3
E) none of the above
Answer: D
5) How is the solubility of a solid affected by temperature?
A) As temperature goes up, the solubility goes up.
B) As temperature goes down, the solubility goes down.
C) As temperature goes up, the solubility goes down.
D) As temperature goes down, the solubility goes up.
E) both A and B
Answer: E
6) How is the solubility of a gas affected by temperature?
A) As temperature goes up, the solubility goes up.
B) As temperature goes down, the solubility goes down.
C) As temperature goes up, the solubility stays the same.
D) As temperature goes down, the solubility goes up.
E) both A and B
Answer: D
7) Describe what usually happens to a hot solution that is saturated with a solid as it cools.
A) The solid that is dissolved comes out of the solution completely.
B) The solid stays in the solution.
C) Some of the solid comes out of the solution.
D) The solution freezes.
E) The solution solidifies.
Answer: C
8) A solid has a solubility at room temperature of 78 grams per liter. If 1.0 L of a hot solution
containing 100. g of solute is cooled to room temperature, how much solid is formed?
A) 22 g
B) 100 g
C) 78 g
D) 1 L
E) 78g/L
Answer: A
9) If the solubility of a compound is 72 grams per liter, how many grams of the compound will
dissolve in 0.50 liters?
A) 36 g
B) 72 g
C) 144 g
D) 30 g
E) none of the above
Answer: A
10) If the solubility of a compound is 30 grams per liter, how much solid is left undissolved if
you mix 30 g of the compound in 0.33 L of solution?
A) 20 g
B) 10 g
C) 0 g
D) 30 g
E) 33 g
Answer: A
11) What property primarily determines the effect of temperature on the solubility of gas
molecules?
A) the kinetic energy of the gas
B) the polarity of the gas
C) the molecular weight of the gas
D) the ionic strength of the gas
E) the dipole strength of the solvent
Answer: A
12) If you were to increase the pressure of a gas above a liquid (such as by pressing a piston
above a liquid) what happens?
A) The gas is forced into solution and the solubility increases.
B) The solution is compressed and the gas is forced out of the solvent.
C) The pressure goes down and the gas moves out of the solvent.
D) The pressure goes down and the gas goes into the solvent.
E) The amount of gas in the solution would stay the same.
Answer: A
13) Under which of the following conditions would you expect the highest solubility of oxygen
gas in water?
A) high temperature and low O2 pressure above the solution
B) low temperature and high O2 pressure above the solution
C) low temperature and low O2 pressure above the solution
D) high temperature and high O2 pressure above the solution
E) The O2 solubility is independent of temperature and pressure.
Answer: B
14) Why does oxygen have such a low solubility in water?
A) Water's attraction for itself is stronger than its attraction for oxygen molecules.
B) Water and oxygen only attract one another by means of weak dipole-induced dipole
attractions.
C) The hydrogen bonding in water keeps the oxygen solubility low.
D) Both A and B are true.
Answer: D
15) Based on atomic size, which would you expect to be more soluble in water: helium, He, or
nitrogen, N2?
A) Although He is smaller, its outer orbital is filled and the atom will have little attraction to the
water molecules.
B) Since He atoms are smaller, more of them can fit into solution, so it has a higher solubility in
water.
C) Nitrogen atoms are bigger and so nitrogen molecules should be more soluble in water due to
greater dipole-induced dipole attractions.
D) He atoms are bigger and so helium molecules should be more soluble in water due to greater
dipole-induced dipole attractions.
Answer: C
16) If nitrogen, N2, were pumped into your lungs at high pressure, what would happen to its
solubility in your blood stream?
A) The greater the pressure, the greater the solubility.
B) The greater the pressure, the lower the solubility.
C) You cannot change solubility of a substance by changing the pressure.
D) Nitrogen is not soluble in your blood.
Answer: A
17) The air that a scuba diver breathes is pressurized to counteract the pressure exerted by the
surrounding water. Under these conditions, excessive amounts of nitrogen dissolves in bodily
fluids, such as blood. If the diver ascends to the surface too rapidly, the excessive nitrogen
bubbles out of the bodily fluids—much like carbon dioxide bubbles out of a soda immediately
after its has been opened. This results in a painful and potentially lethal medical condition known
as the bends. Why does breathing a mixture of helium and oxygen rather than air help divers to
avoid getting the bends?
A) Oxygen and helium have stronger attractions for each other than they do for the blood, so less
helium will be dissolved in the blood and to cause the bends.
B) The helium is less soluble in the bodily fluids and so less dissolves for a given pressure. Upon
decompression, there is less helium to "bubble out" and cause potential harm.
C) The nitrogen in the blood will bind to helium, and so will be exhaled rather than being stuck
in the blood.
D) Helium is a smaller molecule than nitrogen, so when it bubbles out of solution, it is less
painful and less harmful to the body.
Answer: B
18) Why are noble gases infinitely soluble in noble gases?
A) The noble gases are attracted to each other by induced dipole-induced dipole attractions, but
there is only one attraction per molecule.
B) These are the smallest atoms on the periodic table.
C) The molecules do not interact with each other, excluding other molecules.
D) Noble gases can be mixed homogeneously in any proportion.
Answer: D
19) Why does oxygen have such a low solubility in water?
A) Water's attraction for itself is stronger than its attraction for oxygen molecules.
B) Water and oxygen only attract one another by means of weak dipole-induced dipole
attractions.
C) The hydrogen bonding in water keeps the oxygen solubility low.
D) Both A and B are true.
Answer: D
20) How can you tell whether a sugar solution is saturated or not?
A) Add more sugar, if it dissolves, it is saturated.
B) There will be a precipitate if the water is heated.
C) Cool the solution to see if there is a precipitate.
D) As long as there are more water molecules than sugar molecules, there is a saturated solution.
Answer: C
21) Which solute graphed above has a solubility in water that does not markedly increase with
increasing temperature?
A) NaNO3
B) LiCl
C) KCl
D) NaCl
Answer: D
22) At 10°C, which is more concentrated—a saturated solution of sodium nitrate, NaNO3, or a
saturated solution of sodium chloride? (See figure shown above)
A) At 20°C a saturated solution of sodium nitrate, NaNO3, is more concentrated than a saturated
solution of sodium chloride, NaCl.
B) At 10°C a saturated solution of sodium chloride, NaCl, is more concentrated than a saturated
solution of sodium nitrate, NaNO3.
C) At 10°C a saturated solution of sodium nitrate, NaNO3, is more concentrated than a saturated
solution of sodium chloride, NaCl.
D) At 25°C a saturated solution of sodium nitrate, NaNO3, is more concentrated than a saturated
solution of sodium chloride, NaCl.
Answer: C
23) Suggest why sodium chloride, NaCl, is insoluble in gasoline. Consider the electrical
attractions.
A) Since this molecule is so small, there is not much opportunity for the gasoline to interact with
it through any electrical attractions.
B) Since gasoline is a very polar molecule, the salt can only form dipole-induced dipole bonds,
which are very weak, giving it a low solubility in gasoline.
C) Since gasoline is so strongly attracted to itself, the salt, NaCl is excluded.
D) Salt is composed of ions that are too attracted to themselves. Gasoline is non-polar so salt and
gasoline will not interact very well.
Answer: D
24) Deuterium oxide, D2O, and water, H2O, have the same chemical structure and differ only in
that D2O possesses the deuterium isotope of hydrogen, whereas water possesses the protium
isotope. Deuterium oxide, also known as "heavy water," is 11 percent heavier than water. Might
you expect its boiling temperature also to be about 11 percent greater? Why or why not?
A) The mass of the molecules has a far greater influence on the boiling temperature of the
substance than does the polarity of the molecules, so D2O boils at a higher temperature.
B) Since they have the same chemical structures, there is a similar molecular attraction between
the molecules, so their boiling temperatures are similar.
C) Since deuterium is radioactive, it breaks down more easily, so it has a lower boiling
temperature than water.
D) Since boiling temperature is a measure of the speed of a molecule, the heavier molecules
move slower and thus have a higher boiling temperature.
Answer: B
25) Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be
very soluble or not very soluble in water?
A) HCl is very soluble in water by virtue of the dipole/dipole attractions occurring between the
HCl and H2O molecules.
B) It is not very soluble because it is a gas, and all gases have very low solubility in water at
room temperature.
C) HCl is very soluble in water because it is such a small molecule, there is little electrical
attraction to other HCl molecules.
D) It is not very soluble because as a gas with low density, it floats to the surface of the water
and then into the surrounding atmosphere.
Answer: A
26) Would you expect to find more dissolved oxygen in polar or tropical ocean waters? Why?
A) There would be more dissolved oxygen in the tropical oceans because intense tropical storms
mix up the atmospheric oxygen into the ocean water.
B) There would be more dissolved oxygen in the polar oceans because the colder oxygen would
"sink" and dissolve into the water.
C) There would be more dissolved oxygen in the tropical oceans because the heated oxygen
molecules in the air would collide with and mix into the water.
D) There would be more dissolved oxygen in the polar oceans because the solubility of oxygen
in water decreases with increasing temperature.
Answer: D
27) Account for the observation that ethyl alcohol, C2H5OH, dissolves readily in water but
dimethyl ether, CH3OCH3, which has the same number and kinds of atoms, does not.
A) The hydrogens on the dimethyl ether surround the molecule, shielding the inner atoms from
interacting with the water.
B) Because the carbons arrange themselves in a straight line, the ethanol can interact more easily
with more water molecules, thus increasing its solubility.
C) The high electronegativity of the carbon-oxygen-carbon bond on dimethyl ether creates a
strong dipole charge on the ends of the molecule, making it highly soluble in water.
D) Because dimethyl ether lacks an -OH group, it is significantly less polar than is ethyl alcohol
and is not readily soluble in water.
Answer: D
28) When you set a pot of tap water on the stove to boil, you'll often see bubbles start to form
well before boiling temperature is ever reached. Explain this observation.
A) These are dissolved salts heating up and escaping from the water.
B) These bubbles are formed as the surrounding gases from the air dissolve into the water as it is
heated.
C) They are very minute pockets of water in the gaseous phase. When they get large enough, the
water will boil as this gas escapes.
D) These initial bubbles are the gases that were dissolved in the water coming out of solution.
The solubility of gases in water decreases with increasing temperature.
Answer: D
29) Fish don't live very long in water that has just been boiled and brought back to room
temperature. Suggest why.
A) There is now a higher concentration of dissolved CO2 in the water.
B) The nutrients in the water have been destroyed.
C) Since some of the water was evaporated while boiling, the salts in the water are now more
concentrated. This has a negative effect on the fish.
D) The boiling process removes the air that was dissolved in the water. Upon cooling the water is
void of its usual air content, hence, the fish drown.
Answer: D
16.5 Soaps and Detergents
1) Why might a solvent like turpentine be better for removing grease and grime than water?
A) Like dissolves like.
B) Oil and grease have similar interatomic forces as the turpentine and so are more soluble.
C) Water is too polar and doesn't interact well with the nonpolar oils.
D) Oil and grease have very limited solubility in the water.
E) all of the above
Answer: E
2) Which of the following picture might best describe a soap or detergent?
A) a
B) b
C) c
D) d
E) none of the above
Answer: B
3) Which of the above would best describe how soap behaves in water?
A) a
B) b
C) c
D) d
E) none of the above
Answer: D
4) Which of the above might best describe how soap behaves in a nonpolar solvent like
turpentine?
A) a
B) b
C) c
D) d
E) none of the above
Answer: C
5) What is the main difference between a soap and a detergent?
A) Soaps are made from fatty acids, detergents are synthetic.
B) Soaps are biodegradable, detergents are not.
C) Detergents are better than soaps.
D) Soaps are all natural.
E) Soaps and detergents are exactly the same.
Answer: A
6) Which of the following statements does not describes the similarity between soaps and
detergents?
A) They have a polar ionic end and a long nonpolar tail.
B) Both dissolve oils.
C) Both are synthetic.
D) Both are biodegradable.
E) Both are made from fatty acids.
Answer: E
7) How necessary is soap for removing salt from your hands?
A) Soap is necessary because it has both a polar and nonpolar end to interact with the positive
and negative ions in the salt.
B) Soap is necessary because it creates a film on the surface of your skin, shielding it from
interacting with the ionic charges of the salt.
C) Soap is not at all necessary for removing salt from your hands. The strong ion-dipole
interactions between fresh water and the salt are most sufficient to lift the salt away from your
hands.
D) Soap is not necessary because there are no electrical charges on the skin of your hands for the
salt to interact with.
Answer: C
Fatty acid molecules can align to form a barrier called a bilipid layer, shown below. In this
schematic, the ionic end of the fatty acid is shown as a circle and the nonpolar chain is shown as
a squiggly line.
8) From the schematic above: why do nonpolar molecules have a difficult time passing through
the bilipid layer?
A) The nonpolar molecules are too large for the space through which they need to pass.
B) The nonpolar molecules are repelled by the polar water molecules.
C) The nonpolar molecules have a difficult time getting past the ionic heads of the fatty acid
molecules, which are surrounded by water molecules.
D) Nonpolar molecules tend to bind with the bilipid layer, thus inhibiting their passage.
Answer: C
3-
9) Phosphate ions, PO4 , were once added to detergents to assist in cleaning. What function did
they serve?
A) Phosphate ions were relatively good at removing grease by binding with large nonpolar
molecules.
B) Phosphate ions were large enough to bind with the large grime molecules and remove them.
C) Phosphate ions would bind to and remove calcium ions, thus acting as a water softening
agent.
D) Phosphate ions would reduce the growth of algae in aquatic habitats receiving the waste
water.
Answer: C
16.6 Softening Hard Water
1) Which of the following might best describe the product obtained from soap and hard water
(i.e., soap scum)?
A) a
B) b
C) c
D) d
E) none of the above
Answer: C
2) Why might sodium carbonate (washing soda, Na2CO3) be added to hard water to aid in
cleaning?
A) The hard ions in the water are more attracted to the carbonate ions -2 charge.
B) The hard ions are dissolved by the added sodium ions.
C) The soap gets softer due to the added ions.
D) The ions solubilize the soap due to ion-ion intermolecular attraction, which improves the
cleaning ability.
E) none of the above
Answer: A
3) Which of the following statements best describes what is happening in a water softening unit?
A) The hard ions in water are exchanged for ions that do not interact as strongly with soaps.
B) The hard ions are all trapped in the softener, which filets out all the ions.
C) The ions in the water softener are softened by chemically bonding with sodium.
D) The sodium is removed from the water, making the water interact less with the soap
molecules.
E) none of the above
Answer: A
4) Why might softened water not be good for some one who is trying to reduce their dietary
sodium ion intake?
A) The potassium used in the softener to replace the calcium and magnesium ions increases the
sodium retention in the body.
B) Water softeners work by replacing the calcium and magnesium ions of the water with sodium
ions; softened water contains increased levels of sodium ions.
C) The softened water leaches sodium from the body, so a person might not be getting the
dietary recommended levels of sodium.
D) A person needs a certain level of calcium and magnesium in the water to help excrete the
sodium from their body.
Answer: B
5) Why do hot water heaters lose their efficiency quicker in households with hard water?
A) The hard water calcium and magnesium ions corrode the heating element.
B) The hard water calcium carbonate deposits oxidize the inner tank wall.
C) The calcium carbonate on the inner surface of the hot water tank builds up to the point that it
insulates the water from the heating element.
D) The hard water calcium ions exchange with iron ions from the inner metal wall which react
with the water heater base to form rust and deteriorate the bottom of the tank.
Answer: C
6) Fatty acid molecules can also align to form a bilipid layer that extends in 3-dimensions.
Shown below is a cross section of this structure. What is this structure called? (Hint: it forms the
basis of all life)
A) DNA
B) a nucleoside
C) a cell
D) a gene
Answer: C
16.7 Purifying the Water We Drink
1) Which of the following is not a typical use for potable water?
A) irrigation
B) cooking in a pot
C) flushing a toilet
D) drinking
E) boiling
Answer: A
2) Water being purified using aluminum salts and a base is an example of ________.
A) a physical separation
B) a chemical reaction
C) an acid-base reaction
D) a chemical separation
E) none of the above
Answer: A
3) What is the purpose of adding aluminum salts and a base to water during water treatment?
A) The two together gel and trap dirt and bacteria.
B) The higher pH kills bacteria.
C) The aluminum removes the rust taste from the water
D) The base dissolves the dirt.
E) It improves the taste.
Answer: A
4) Allowing water to cascade or bubble in a fountain during the purification process is an
example of ________.
A) a gas dissolving in a liquid
B) a chemical reaction
C) ion exchange
D) a solid dissolving in a liquid
E) only A and B
Answer: A
5) What is the purpose of allowing water to cascade or bubble in a fountain during the
purification process?
A) to mix air into the water and improve flavor
B) to remove radioactive gases
C) to remove unpleasant smelling chemicals like sulfur
D) all of the above
E) only A and B
Answer: D
6) What is the purpose of treating water with chlorine gas or ozone during water purification?
A) to kill bacteria
B) to improve taste
C) to improve color
D) to remove solids
E) none of the above
Answer: A
7) Treating water with chlorine or ozone during water purification is an example of ________.
A) a physical change
B) a chemical reaction
C) ion exchange
D) a solid dissolving in a liquid
E) only A and B
Answer: B
8) Passing arsenic contaminated water through a long pipe filled with sand and iron powder leads
to removal of the arsenic by ________.
A) a physical change
B) an oxidation-reduction reaction
C) ion exchange
D) filtering out the suspended arsenic particles
E) only A and B
Answer: B
9) Why isn't distillation used commercially to purify water?
A) Water requires large amounts of energy to boil affordably.
B) Bacteria are not killed during the distillation process.
C) Odd smelling contaminants boil at lower temperatures than water and so are impossible to
remove.
D) Distillation does not remove suspended particles such as dirt and humus.
E) none of the above
Answer: A
10) Why aren't solar stills used in more large urban areas?
A) They take up too much space.
B) They do not produce enough water.
C) They require too much sunlight.
D) They are not as efficient are reverse osmosis.
E) all of the above
Answer: A
11) What is the special property of a semipermeable membrane that makes osmosis possible?
A) The pores in the membrane only allow water to pass through.
B) Water only moves through the membrane in one direction.
C) Only the ions travel through the membrane.
D) Ions only move one way through the membrane.
E) none of the above
Answer: A
12) What makes a semipermeable membrane selective for one chemical species but not another?
A) The pores in the membrane select by size, they are big enough for water only.
B) The material is hydrophilic and therefore only allows water through.
C) The material is hydrophobic and therefore only allows water through.
D) The material chemically reacts with everything but water.
E) none of the above
Answer: A
13) Which of the following accurately describes osmosis?
A) The more concentrated solution absorbs water from the less concentrated solution.
B) The less concentrated solution absorbs water from the more concentrated solution.
C) The less concentrated solution gets more dilute.
D) The ions migrate from the more concentrated solution to the less concentrated.
E) none of the above
Answer: A
14) During osmosis ________.
A) the water moves into the concentrated solution faster than it leaves
B) the ions move into the concentrated solution faster than they leave
C) the water moves more slowly into the concentrated solution than it leaves
D) the ions move into the concentrated solution slower than they leave
E) all of the above
Answer: A
15) What happens if you were to place a concentrated solution into a bag made of a
semipermeable membrane and were to then suspend it in a very dilute solution?
A) The size of the suspended bag would decrease.
B) The size of the suspended bag would increase.
C) The size of the bag would not change.
D) The solutions would eventually reach the same concentration.
E) only C and D
Answer: B
16) What happens if you were to place a dilute solution that is in a bag made of a semipermeable
membrane and were to then suspend it in a very concentrated solution?
A) The size of the suspended bag would decrease.
B) The size of the suspended bag would increase.
C) The size of the bag would not change.
D) The solutions would eventually reach the same concentration.
E) only C and D
Answer: A
17) Which of the following statements about desalinization is untrue?
A) You can use osmosis to remove salt from saltwater.
B) You can use distillation to separate salt from saltwater.
C) Desalinization is an energy intensive process.
D) All are untrue.
E) Only A and B are untrue.
Answer: A
18) Which of the following describes reverse osmosis?
A) High pressure saltwater is forced against a semipermeable membrane and fresh water comes
out.
B) Saltwater is chemically reacted with aluminum particles, which chemically binds to the
chloride ions.
C) The water is heated until it evaporates and condenses in a pure form.
D) High pressure saltwater is reacted with aluminum, which absorbs the sodium ions in an
oxidation reaction.
E) none of the above
Answer: A
19) Which of the following would cost the least to purify by reverse osmosis?
A) agricultural runoff
B) sea water
C) brackish water
D) All of the above are the same.
E) None of the above can be purified by reverse osmosis.
Answer: A
20) Red blood cells have a high concentration of dissolved ions. When placed into pure water
they rupture. Why?
A) Osmosis draws water into the cell until it pops.
B) Water dissolves the cell membrane.
C) Osmosis draws water out of the cell until it tears.
D) The cells are not stable outside of a biological host.
E) none of the above
Answer: A
21) Why is it important to conserve fresh water?
A) There is little fresh water available to us on our planet.
B) As the human population grows, so does our need for fresh water.
C) It is expensive to purify nonpotable water.
D) all of the above
Answer: D
22) Might reverse osmosis be used to obtain fresh water from a sugar-water solution?
A) No, osmosis and reverse osmosis only apply to aqueous solutions containing ions.
B) Yes, reverse osmosis can be applied to any aqueous solution for the generation of fresh water.
C) No, the molecular attractions between sugar and water are too strong.
D) Yes, because sugar molecules are smaller than sodium or chloride ions.
Answer: B
23) Cells at the top of a tree have a higher concentration of sugars than cells at the bottom. How
might this fact assist a tree in moving water upward from its roots?
A) Cells with high concentrations of sugar are more dense. As these cells migrate downwards,
cells containing fresh water are able to migrate upwards.
B) Water is pushed upwards by osmostic pressure.
C) It doesn't. In fact, water makes it to the top of a tree because that is where the water molecules
are being evaporated.
D) Fresh water is drawn upwards to the sugar containing cells by way of dipole-dipole molecular
interactions.
Answer: B
24) Why is it significantly less costly to purify fresh water through reverse osmosis than to purify
salt water through reverse osmosis?
A) The osmotic pressure exerted by fresh water is less.
B) The osmotic pressure exerted by fresh water is greater.
C) For non-coastal regions, the salt water needs to be transported many miles from the oceans.
D) The expense of reverse osmosis is not dependent upon the salt concentration in the water.
Answer: A
25) Why do red blood cells, which contain an aqueous solution of dissolved ions and minerals,
burst when placed in fresh water?
A) The dissolved ions provide a pressure that eventually bursts open the cell.
B) More water molecules enter the cell than leave the cell.
C) The fresh water acts to dissolve the blood cell wall.
D) all of the above
Answer: C
26) Some people fear drinking distilled water because they have heard it leaches minerals from
the body. What scientifically sound information might be offered to such a person?
A) add small amounts of salt to the distilled water before drinking it
B) chill the distilled water to decrease its leaching potential
C) buy distilled water that has also undergone reverse osmosis
D) Distilled water is relatively pure water, which loses its purity once it mixes with everything
else in your stomach.
Answer: D
27) How does the purchase and use of a home beverage carbonator help to minimize carbon
dioxide emissions?
A) It allows the consumer to avoid using commercial sodas that require much gasoline for
shipping.
B) Home carbonators are more efficient at forcing the carbon dioxide into solution.
C) Industrial carbonators are driven by mechanical pumps that require large amounts of gasoline
in order to operate.
D) False. Home carbonators have the net effect of producing more carbon dioxide per liter of
carbonate water.
Answer: A
16.8 Wastewater Treatment
1) Does the concentration of chlorine in drinking water tend to increase or decrease as it leaves
the water treatment plant and disperses into the community? Why?
A) Increases. As the chlorine reacts with the bacteria in the water, more chlorine is produced.
B) Increases. As the water evaporates the chlorine concentration would increase in the remaining
water.
C) Decreases. Evaporative processes and reaction with organic bacteria would decrease the
chlorine concentration.
D) Neither. The chlorine concentration in the water does not vary as the water is dispersed into
the community.
Answer: C
2) Which of the following statements about sewage is not true?
A) All municipalities must treat sewage the same way.
B) All municipalities must treat sewage.
C) Once treated, sewage is released to the environment.
D) Treated sewage becomes drinking water downstream.
E) None of the above are true.
Answer: A
3) What is the first step in treating raw sewage?
A) filtration of solids
B) removal of fine particles by settling
C) removal of grit by settling
D) removal of sludge
E) disinfection
Answer: A
4) Why is secondary treatment often needed for sewage?
A) The dissolved organics are too high and lead to bacterial growth.
B) The solution is contaminated with dangerous bacteria.
C) There are too many dissolved inorganic compounds.
D) There are too many finely divided particles that need to be filtered.
E) none of the above
Answer: A
5) What is the easiest way to eliminate organic components?
A) Aerate the solution and let bacteria consume the organics.
B) Treat the solution with UV radiation.
C) Filter the solution through activated carbon filters.
D) reverse osmosis
E) all of the above
Answer: A
6) How is most of the energy required for secondary waste water treatment consumed?
A) as electricity to power air pumps for aeration
B) as electricity to illuminate UV lamps
C) as heat to run distillation equipment
D) as electricity to power hydraulic pumps for reverse osmosis
E) none of the above
Answer: A
7) What is an advantage of using chlorine gas to disinfect drinking water supplies?
A) It provides residual protection against pathogens.
B) It gives the water a fresh taste.
C) Residual chlorine in water helps to whiten teeth.
D) Excess chlorine is absorbed in our bodies as a mineral supplement.
Answer: A
8) Why is flushing a toilet with clean water from a municipal supply about as wasteful as
flushing it with bottled water?
A) Bottled water is typically made from municipal water.
B) Municipal water and bottle water have about the same level of purity.
C) Both the bottled water and municipal water are generally free of pathogens.
D) all of the above
Answer: D
9) Where does most of the solid mass of raw sewage end up after being collected at a treatment
facility?
A) It is injected into the water table.
B) It is buried in landfills.
C) It is sold to farmers for fertilizer.
D) It is tapped for the generation of methane gas.
Answer: B
10) Why are there few odors emanating from a properly managed composting toilet?
A) Tight seals prevent the escape of odors.
B) Odors are absorbed by a layer of water.
C) Decomposition is aerobic.
D) The ventilation system steers odors through a carbon filter.
Answer: C
Test Bank for Conceptual Physical Science
Paul Hewitt, John Suchocki, Leslie Hewitt
9780321752932, 9780134060491
