Chapter 3 AP Bio Midterm

Assume that acid rain has lowered the pH of a particular lake to pH 4.0. What is the hydroxyl ion concentration of this lake? A) 1 × 10-10 mol of hydroxyl ion per liter of lake water B) 1 × 10-4 mol of hydroxyl ion per liter of lake water C) 10.0 M with regard to hydroxyl ion concentration D) 4.0 M with regard to hydroxyl ion concentration E) both B and D

A) 1 × 10-10 mol of hydroxyl ion per liter of lake water

The molecular weight of water is 18 daltons. What is the molarity of 1 liter of pure water? A) 55.6M B) 18M C) 37M D) 0.66M E) 1.0 M

A) 55.6M

Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O →H2CO3. Carbonic acid (H2CO3) is a weak acid. Respiring cells release CO2. What prediction can we make about the pH of blood as that blood first comes in contact with respiring cells? A) Blood pH will decrease slightly. B) Blood pH will increase slightly. C) Blood pH will remain unchanged. D) Blood pH will first increase, then decrease as CO2 combines with hemoglobin. E) Blood pH will first decrease, then increase sharply as CO2 combines with hemoglobin.

A) Blood pH will decrease slightly.

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+). Thus, H2CO3 ↔ HCO3- + H+ If the pH of the blood increases, one would expect A) a decrease in the concentration of H2CO3 and an increase in the concentration of H2O. B) an increase in the concentration of H2CO3 and a decrease in the concentration of H20 C) a decrease in the concentration of HCO3 and an increase in the concentration of H20 D) an increase in the concentration of HCO3 and a decrease in the concentration of H20 E) a decrease in the concentration of HCO3 and an increase in the concentration of both H2CO3 and H20

A) a decrease in the concentration of H2CO3 and an increase in the concentration of H2O.

Which of the following solutions has the greatest concentration of hydrogen ions [H +]? A) gastric juice at pH 2 B) vinegar at pH 3 C) tomato juice at pH 4 D) black coffee at pH 5 E) household bleach at pH 12

A) gastric juice at pH 2

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10-12 M? A) pH 2 B) pH 4 C) pH 10 D) pH 12 E) pH 14

A) pH 2

The molecular mass of glucose is 180 g. Which of the following procedures should you carry out to make a .5 M solution of glucose? A) Dissolve 0.5 g of glucose in a small volume of water, and then add more water until the total volume of solution is 1 L. B) Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. C) Dissolve 180 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. D) Dissolve 0.5 g of glucose in 1 L of water. E) Dissolve 180 g of glucose in 1 L of water.

B) Dissolve 90 g of glucose in a small volume of water, and then add more water until

Which of the following ionizes completely in solution and is considered to be a strong acid? A) NaOH B) HCl C) NH3 D) H2CO3 E) CH3COOH

B) HCl

Equal volumes of vinegar from a freshly-opened bottle are added to each of the following solutions. After complete mixing, which of the mixtures will have the highest pH? A) 100 mL of pure water B) 100 mL of freshly-brewed coffee C) 100 mL of household cleanser containing .5M ammonia D) 100 mL of freshly-squeezed orange juice E) 100mL of tomato juice

C) 100 mL of household cleanser containing .5M ammonia

You have a freshly-prepared 1M solution of glucose in water. You carefully pour out a 100 mL sample of that solution. How many glucose molecules are included in that 100 mL sample? A) 6.02 × 1023 B) 3.01 × 1023 C) 6.02 × 1024 D) 12.04 × 1023 E) 6.02 × 1022

C) 6.02 × 1024

A given solution contains 0.0001(10-4) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution? A) acidic: H+ acceptor B) basic: H+ acceptor C) acidic: H+ donor D) basic: H+ donor E) neutral

C) acidic: H+ donor

If the pH of a solution is increased from pH 5 to pH 7, it means that the A) concentration of H+ is twice (2X) what it was at pH 5. B) concentration of H+ is half (1/2) what it was at pH 5. C) concentration of OH- is 100 times greater than what it was at pH 5. D) concentration of OH- is one-hundredth (0.01X) what it was at pH 5. E) concentration of H+ is 100 times greater and concentration of OH- is one-hundredth what they were at pH 5

C) concentration of OH- is 100 times greater than what it was at pH 5.

Pure, freshly-distilled water has a pH of 7. This means that A) there are no H+ ions in the water. B) there are no OH- ions in the water. C) the concentration of H+ ions in the water equals the concentration of OH- ions in the water. D) the concentration of H+ ions in the water is 7 times the concentration of OH- ions in the water. E) The concentration of OH- ions in the water is 7 times the concentration of H+ ions in the water.

C) the concentration of H+ ions in the water equals the concentration of OH- ions in the water.

One liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 L of a solution of pH 6? A) 4 times more B) 400 times more C) 4,000 times more D) 10,000 times more E) 100,000 times more

D) 10,000 times more

Which of the following statements is completely correct? A) H2CO3 is a weak acid, and NaOH is a weak base (alkali). B) H2CO3 is a strong acid, and NaOH is a strong base (alkali). C) NH3 is a weak base (alkali), and H2CO3 is a strong acid. D) NH3 is a weak base (alkali), and HCl is a strong acid. E) NH3 is a strong base (alkali), and HCl is a weak acid.

D) NH3 is a weak base (alkali), and HCl is a strong acid.

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+ If the pH of the blood drops, one would expect A) a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-. B) the concentration of hydroxide ion (OH-) to increase. C) the concentration of bicarbonate ion (HCO3-) to increase. D) the HCO3- to act as a base and remove excess H+ with the formation of H2CO3. E) the HCO3- to act as an acid and remove excess H+ with the formation of H2CO3

D) the HCO3- to act as a base and remove excess H+ with the formation of H2CO3.

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? A) waterʹs change in density when it condenses B) waterʹs ability to dissolve molecules in the air C) the release of heat by the formation of hydrogen bonds D) the absorption of heat by the breaking of hydrogen bonds E) waterʹs high surface tension

D) the absorption of heat by the breaking of hydrogen bonds

Which of the following statements is true about buffer solutions? A) They maintain a constant pH when bases are added to them but not when acids are added to them. B) They maintain a constant pH when acids are added ti them but not when bases are added to them c) they maintain a constant pH of exactly 7 in all living cells and biological fluids D) they maintain a relatively constant pH when either acids or bases are added to them E) They are found only in living systems and biological fluids

D) they maintain a relatively constant pH when either acids or bases are added to them

Buffers are substances that help resist shifts in pH by A) releasing H+ in acidic solutions. B) donating H+ to a solution when they have been depleted. C) releasing OH- in basic solutions. D) accepting H+ when the are in excess. E) Both B and D are correct.

E) Both B and D are correct.

If the pH of a solution is decreased from 9 to 8, it means that the A) concentration of H+ has decreased to one-tenth (1/10) what it was at pH 9. B) concentration of H+ has increased 10-fold (10X) compared to what it was at pH 9. C) concentration of OH- has increased 10-fold (10X) compared to what it was at pH 9. D) concentration of OH- has decreased to one-tenth (1/10) what it was at pH 9. E) Both B and D are correct.

E) Both B and D are correct.

Which of the following ionizes completely in solution and is considered to be a strong base (alkali)? A) NaCl B) HCl C) NH3 D) H2CO3 E) NaOH

E) NaOH

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 A) solution Y has no free hydrogen ions (H+). B) the concentration of hydrogen ions in solution X is 30 times as great as the concentration of hydrogen ions in solution Y. C) the concentration of hydrogen ions in solution Y is 1,000 times as great as the concentration of hydrogen ions in solution X. D) the concentration of hydrogen ions in solution X is 3 times as great as the concentration of hydrogen ions in solution Y. E) None of the other answer choices correctly describes these solutions.

E) None of the other answer choices correctly describes these solutions.

A solution contains 0.0000001(10-7) moles of hydroxyl ions [OH-] per liter. Which of the following best describes this solution? A) acidic: H+ acceptor B) basic: H+ acceptor C) acidic: H+ donor D) basic: H+ donor E) neutral

E) neutral

Which of the following solutions has the greatest concentration of hydroxyl ions [OH-]? A) lemon juice at pH 2 B) vinegar at pH 3 C) tomato juice at pH 4 D) urine at pH 6 E) seawater at pH 8

E) seawater at pH 8

A 100 mL beaker contains 10 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 results of this mixing? A) The concentration of Na+ ion rises. B) The concentration of Cl- ion falls. C) The concentration of undissociated H2O molecules remains unchanged D) the pH of the beaker's contents rises E) the pH of the beaker's contents falls

E) the pH of the beaker's contents falls

water's high specific heat is mainly a consequence of the_______

absorption and release of heat when hydrogen bonds break and form

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

polar covalent bonds

what type of bond must be broken for water to vaporize?

hydrogen bonds

You have a freshly-prepared 0.1M solution of glucose in water. Each liter of this solution contains how many glucose molecules? A) 6.02 × 1023 B) 3.01 × 1023 C) 6.02 × 1024 D) 12.04 × 1023 E) 6.02 × 1022

C) 6.02 × 1024

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. A) Equal amounts of NaCl crystals will dissolve in both water and methanol. B) NaCl crystals will NOT dissolve in either water or methanol. C) NaCl crystals will dissolve readily in water but will not dissolve in methanol. D) NaCl crystals will dissolve readily in methanol but will not dissolve in water. E) When the first crystals of NaCl are added to water or to methanol, they will not dissolve; but as more crystals are added, the crystals will begin to dissolve faster and faster.

C) NaCl crystals will dissolve readily in water but will not dissolve in methanol.

Research indicates that acid precipitation can damage living organisms by A) buffering aquatic systems such as lakes and streams. B) decreasing the H+ concentration of lakes and streams. C) increasing the OH- concentration of lakes and streams. D) washing away certain mineral ions that help buffer soil solution and are essential nutrients for plant growth. E) both B and C

D) washing away certain mineral ions that help buffer soil solution and are essential nutrients for plant growth.

example of a hydrogen bond is the bond between: a. C and H in methane (CH4) b. H of one water molecule and the O of another water molecule c. Na and Cl in salt d. the two hydrogen atoms in a molecule of hydrogen gas e. Mg and Cl in MgCl2

b. H of one water molecule and O of another water molecule

which of the following effects is produced by the high surface tension of water? a. lakes don't freeze solid in winter, despite low temperatures b. a water strider can walk across the surface of a small pond c. organisms resist temperature changes, although they give ff heat due to chemical reactions d. water can act as a solvent e. the pH of water remains exactly neutral

b. a water strider can walk across the surface of a small pond

When NaCL is placed in water, the component atoms dissociate into individual sodium and chloride ions. In contrast, the atoms of covalently bonded molecules (glucose) don't usually dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of particles (molecules or ions)? a. 1 L of .5 M NaCl b. 1 L of .5 M glucose c. 1 L of 1.0 M NaCl d. 1 L of 1.0 M glucose e. C and D will contain equal number of particles

c. 1 L of 1.0 M NaCl

You have two beakers. One contains a solution of HCl at pH = 1.0. The other contains a solution of NaOH at pH = 13. Into a third beaker, you slowly and cautiously pour 20 mL of the HCL and 20 mL of the NaOH. After complete stirring, the pH of the mixiture will be a. 2 b. 12 c. 7 d. 5 e. 9

c. 7

The molecular mass of glucose is 18 g. Which of the following should you carry out to make a 1 M solution of glucose? a. dissolve 1 g of gluocse in 1 L of water b. dissolve 180 g of glucose in 1 L of water c. dissolve 180 g of glucose in 100 g of water d. dissolve 180 mg of glucose in 1 L of water e. dissolve 180 g of glucose in water, then add more water until the total volume of the solution is 1 L

e. dissolve 180 g of glucose in water, then add more water until the total volume of the solution is 1 L

the slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?

hydrogen bond

why does ice float in liquid water?

hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water

hydrophobic substances such as vegetable oil are

nonpolar substances that repel water molecules

we can be sure that a mole of table sugar and mole of vitamin C are equal in their

number of molecules

What is a kilocalorie?

the amount of heat required to raise the temperature of 1 kg of water by 1 degrees C

Water is able to form hydrogen bonds because

the bonds that hold together the atoms in a water molecule are polar covalent bonds

one mole of a substance is

the molecular mass of the substance expressed in gram (6.02 X 10^23 molecules of the substance)

What behavior of water is most directly responsible for the temperature increase that occurs when water condenses?

the release of heat by the formation of hydrogen bonds

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.) A) 50°C B) 5°C C) 10°C D) 100°C E) 1°C

C) 10°C

At what temperature is water at its densest? a. 0 degrees C b. 4 degrees C c. 32 degrees C d. 100 degrees C e. 212 degrees C

b. 4 degrees C

Which of the following is a hydrophobic material? a. paper b. table salt c. wax d. sugar e. pasta

c. wax

what gives rise to the cohesiveness of water molecules

hydrogen bonds

what takes place when an ice cube cools a drink?

kinetic energy in the drink decreases

Based on your knowledge of the polarity of water molecules, the solute molecule is most likely_______

positively charged