Chapter 3 Test Bank AP Bio

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 particles (molecules or ions)

1 Lof 1.0 MNaCl

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

1 × 10-10 mol of hydroxyl ion per liter of lake 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

10,000 times more

The nutritional information on a cereal box shows that one serving of a dry cereal has 200 kilocalories. If one were to burn one serving of the cereal, the amount of heat given off would be sufficient to raise the temperature of 20 kg of water how many degrees Celsius

10.0°C

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

100 mL of household cleanser containing 0.5M ammonia

One liter of a solution pH 9 has how many more hydroxyl ions (OH -) than 1 L of a solution of pH 4

100,000 times more

At what temperature is water at its densest?

4°C

The molecular weight of water is 18 daltons. What is the molarity of 1 liter of pure water

55.6M

How many molecules of glucose (C6H2O6 molecular mass =180 daltons) would be present in one mole of glucose

6.02 × 1023

How many molecules of glycerol (C3H8O3) would be present in 1 L of a 1 M glycerol solution?

6.02 × 1023

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

6.02 × 1024

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 mixture will be

7.0.

One mole (mol) of a substance is

A and D (6.02 x 10^23 molecules of the substance, the molecular mass of the substance is expressed in grams)

Which of the following effects is produced by the high surface tension of water

A water strider can walk across the surface of a small pond

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

Blood pH will decrease slightly

If the pH of a solution is decreased from 9 to 8, it means that the

Both B and D (concentration of H+ has increased 10-fold (10X) compared to what it was at pH 9, concentration of OH- has decreased to one-tenth (1/10) what it was at pH 9)

Buffers are substances that help resist shifts in pH by

Both B and D (donating H+ to a solution when they have been depleted, accepting H+ when the are in excess)

The molecular mass of glucose is 180 g. Which of the following procedures should you carry out to make a 1 M solution of glucose

Dissolve 180 g of glucose in water, and then add more water until the total volume of the solution is 1 L

The molecular mass of glucose (C6H12O6) is 180 g. Which of the following procedures should you carry out to make a 0.5 M solution of glucose

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

Which of the following ionizes completely in solution and is considered to be a strong acid

HCl

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

Which of the following takes place as an ice cube cools a drink

Kinetic energy in the drink decreases

Which of the following statements is completely correct

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

You have two beakers; one contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen

NaCl crystals will dissolve readily in water but will not dissolve in methanol

Which of the following ionizes completely in solution and is considered to be a strong base (alkali)

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

None of the other answer choices correctly describes these solutions

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

The pH of the beakerʹs contents falls

Which of the following statements is true about buffer solutions

They maintain a relatively constant pH when either acids or bases are added to them

One of the buffers that contribute to pH stability in human blood is carbonic acid H2CO3. Carbonic acid is a weak acid that when placed in an aqueous solution dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+ If the pH of the blood increases, one would expect

a decrease in the concentration of H2CO3 and an increase in the concentration of H2O

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

a hydrogen bond

Waterʹs high specific heat is mainly a consequence of the

absorption and release of heat when hydrogen bonds break and form

A given solution contains 0.0001(10-4) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution

acidic: H+ donor

If the pH of a solution is increased from pH 5 to pH 7, it means that the

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

Which of the following solutions has the greatest concentration of hydrogen ions [H +]

gastric juice at pH 2

What gives rise to the cohesiveness of water molecules

hydrogen bonds

Which type of bond must be broken for water to vaporize

hydrogen bonds

A solution contains 0.0000001(10-7) moles of hydroxyl ions [OH-] per liter. Which of the following best describes this solution

neutral

Hydrophobic substances such as vegetable oil are

nonpolar substances that repel water molecules

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10-12 M

pH 2

What is the pH of a solution with a hydrogen ion [H+] concentration of 10-8 M

pH 8

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

polar covalent bonds

Which of the following solutions has the greatest concentration of hydroxyl ions [OH-]

seawater at pH 8

An example of a hydrogen bond is the bond between

the H of one water molecule and the O of another water molecule

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

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

Which of the following statements correctly defines a kilocalorie

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

Water is able to form hydrogen bonds because

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

Pure, freshly-distilled water has a pH of 7. This means that

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

Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon

the release of heat by the formation of hydrogen bonds

Research indicates that acid precipitation can damage living organisms by

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