Biology Test Chapter 3

The pH of the beaker's contents falls

A 100mL beaker contains 10mL 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?

acidic: H+ donor

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

10 Celsius

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.)

0.5 kilocalories per gram of wax burned

A small birthday candle is weighed, then lighted and placed beneath a metal can containing 100mL of water. Careful records are kept as the temperature of the water rises. Data from this experiment are shown on the graph. What amount of heat energy is released in the burning of candle wax?

neutral

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

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

An example of a hydrogen bond is the bond between

1 x 10^-10 mole of hydroxyl ion per liter of lake water

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?

4 celcius

At what temperature is water at its densest?

positively charged.

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

Both B and D are correct

Buffers are substances that help resist shifts in pH by

C

Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O -> H2CO3. Carbonic acid (H2CO3) is a weak acid. If CO2 is bubbled into a beaker containing pure, freshly- distilled water, which of the following graphs correctly describes the results?

Blood pH will decrease slightly

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?

None of the other answer choices correctly describes these solutions

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

100 mL of household cleanser containing o.5M ammonia

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?

60.0g

How many grams of acetic acid (C2H4O2) would you use to make 10 L of 0.1 M aqueous solution of acetic acid? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for Oxygen.)

60

How many grams of the molecule in Figure 3.2 would be equal to 1 Mol of the molecule? (Carbon =12, Oxygen = 16, Hydrogen =1)

30

How many grams of the molecule in Figure 3.2 would be required to make 1 L of a 0.5 M solution of the molecule? (Carbon =12, Oxygen =16, Hydrogen =1)

150

How many grams of the molecule in Figure 3.2 would be required to make 2.5L of a 1 M solution of the molecule? (Carbon =12, Oxygen =16, Hydrogen =1)

6.02 x 10^23

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

6.02 x 10^23

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

nonpolar substances that repel water molecules

Hydrophobic substances such as vegetable oil are

B

Identical heat lamps are arranged to shine on an identical container of water and methanol (wood alcohol) so that each liquid absorbs the same amount of energy minute by minute. The covalent bonds of methanol molecules are non- polar, so there are no hydrogen bonds among methanol molecules. Which of the following graphs correctly describes what will happen to the temperature of water and the methanol?

Both B and D are correct

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

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

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

polar covalent bonds

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

the absorption of heat by the breaking of hydrogen bonds

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?

10^ -4 M

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?

10,000 times more

One liter of a solution of pH 2 has how many more hydrogens ions (H+) than 1 L of a solution of pH 6?

100,000 times more

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

A and D only

One mole (mol) of a substance is

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

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, if the pH of the blood drops, one would expect

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

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, if the pH of the blood increases, one would expect

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

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

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

Research indicates that acid precipitation can damage living organisms by

the release of heat by the formation of hydrogen bonds

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

hydrogen bonds between water moles

The bonds that are broken when water vaporizes are

Dissolve 90g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L.

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

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

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

55.6 M

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

10.0 Celius

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 20kg of water how many degrees Celcius?

a hydrogen bond

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?

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

Water is able to form hydrogen bonds because

absorption and release of heat when hydrogen bonds break and form

Water's high specific heat is mainly a consequence of the

number of moles

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

hydrogen bonds

What gives rise to the cohesiveness of water molecules?

10 ^-10 M

What is the hydroxide ion concentration of the lake described in question 7?

pH 8

What is the pH of a solution with a hydrogen ion (H+) concentration of 10^-8 M?

pH 2

What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10^-12 M?

1 L of 1.0 M NaCl

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)?

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

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

HCl

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

NaOH

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

wax

Which of the following is a hydrophobic material?

gastric juice at pH 2

Which of the following solutions has the greatest concentration of hydrogen ions (H+)?

seawater at pH 8

Which of the following solutions has the greatest concentration of hydroxyl ions (OH-)?

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

Which of the following statements correctly defines a kilocalorie?

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

Which of the following statements is completely correct?

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

Which of the following statements is true about buffer solutions?

Kinetic energy in the drink decreases

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

hydrogen bonds

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

Hydrogen bonds stabilize and keep the molecules of ice further apart than the molecules of liquid water.

Why does ice float in liquid water?

6.02 x 10^24

You have a freshly- prepared 0.1M solution of glucose in water. Each liter of this solution contains how many glucose molecules?

6.02 x 10^24

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 100mL sample?

7.0

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

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

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.