Mastering Bio Ch 3

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

10,000 times more

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

10-10 M

A pH of 6 is how many times more acidic than a pH of 9?

1000

The molar mass of glucose is 180 grams per mole (g/mol). Which of the following procedures should you carry out to make a 1 M solution of glucose? Into 0.8 liter (L) of water, dissolve _____.

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

How many grams of the compound in the figure above are required to make 1 liter of a 0.5 M solution? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)

30

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 10^23

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

6.02 × 10^22

The concentration of the appetite-regulating hormone ghrelin is about 1.3 × 10^-10 M in the blood of a fasting person. How many molecules of ghrelin are in 1 L of blood?

7.8 × 10^13

Select the statement that best describes a buffer.

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.

Which of the following effects can occur because of the high surface tension of water?

A raft spider can walk across the surface of a small pond.

Identify all correct statements about the ionization of water.

Dissociation of water produces equal numbers of OH- and H+. Dissociation of water is reversible. Water ionizes to form hydroxide and hydronium ions.

In living systems molecules involved in hydrogen bonding almost always contain either oxygen or nitrogen or both. How do you explain this phenomenon?

Oxygen and nitrogen are elements with very high attractions for their electrons.

A beaker contains 100 milliliters (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 result of this mixing?

The pH of the beaker's contents will decrease.

The loss of water from a plant by transpiration cools the leaf. Movement of water in transpiration requires both adhesion to the conducting walls and wood fibers of the plant and cohesion of the molecules to each other. A scientist wanted to increase the rate of transpiration of a crop species to extend its range into warmer climates. The scientist substituted a nonpolar solution with an atomic mass similar to that of water for hydrating the plants. What do you expect the scientist's data will indicate from this experiment?

Transpiration rates will fall to zero as nonpolar compounds do not have the properties necessary for adhesion and cohesion.

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+), as noted below. H2CO3<-->HCO3-+H+ If the pH of blood increases, one would expect _____.

a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-

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

a hydrogen bond

Which property of water allows a paper towel to pick up a puddle of water?

adhesion of water molecules to

Many of water's emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules _____.

are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively

A strong acid like HCl _____.

dissociates completely in an aqueous solution

Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _____

high specific heat

Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as _____

hydrogen bonds

An acid is a substance that _____.

increases the hydrogen ion concentration of an aqueous solution

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, then the concentration of H+ ions _____.

is 10 times higher in the cytoplasm than in the mitochondrial matrix

Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S will _____.

not form hydrogen bonds with each other

Which property of water allows dogs to cool themselves by panting?

water's high heat of vaporization

Which property of water allows a water strider to walk on water?

water's high surface tension

Which of the following is a hydrophobic material?

wax