Bio 151: chapter 2

A base is a substance that

lowers [H+] and increases the pH when it dissociates in water

dilution equation

C1V1=C2V2

A(n) ________molecule can break apart to form a positive hydrogen ion and a negative hydroxide ion.

water

If an atom gains or loses a(n) , it acquires a net electrical charge and becomes an ion.

electron

Order the following atoms in increasing order of their electronegativity, starting at the top with the leastelectronegative one.

1.H 2.C 3.N 4.O

Which of the following statements about nonpolar molecules are true?

1.They are electrically neutral 2The distribution of electrical charge is uniform

Which of the following statements about polar molecules are true?

1.They are electrically neutral. 2.They have the same number of protons and electrons.

Hydrogen bonds are important for which reasons?

1.They help maintain the structure of DNA and proteins. 2.They play a key role in determining the properties of water.

Acidosis refers to a(n) ______ in the pH of human blood, and alkalosis refers to a(n) ______ in the pH of human blood.

1.decrease; 2. increase

Buffers stabilize the pH of solutions by ______ hydrogen ions when a base is added and ______ hydrogen ions when an acid is added.

1.releasing; 2.absorbing

When 1 g of sugar is dissolved in 500 mL of water, the sugar is called the ______and water is called the______________

1.solute 2.solvent

The angle between the two O-H covalent bonds in a molecule of water is how many degrees (to the tenth place)?

104.5

A molar concentration of 2 M is equal to:

2 mol/L

One mole of sucrose contains how many molecules?

6.02 x 10^23

If a person's pH has a value of 7.1, that person is said to exhibit

acidosis

Because polar water molecules attract each other, water is said to be____

cohesive

Water consists of one oxygen atom joined to two hydrogen atoms by two single, polar_________bonds

covalent

When electrons move closer to the nucleus,

energy is released.

The________ charges produced by a polar covalent bond are much smaller than the unit charge of an ion.

partial

Which of the following are structural formulas?

H-H O-O

Atoms are composed of which of the following?

Subatomic particles

If two electrons occupy different orbitals, they

may or may not have the same potential energies.

Isotopes differ in the number of _________they contain.

neutrons

Water tends to repel or exclude which of the following?

1. Hydrophobic molecules 2. non polar molecules

Rank the following bonds and interactions in order from strongest to weakest starting with the strongest at the top. When ranking the bonds, assume that they occur in a biological system, i.e. chemical compounds are dissolved in water.

1. covalent 2.ionic 3. hydrogen 4. hydrophobic 5. van der waals

When 1 g of fructose is dissolved in 500 mL of water__________, is the solvent and___________ is the solute.

1. water 2. fructose

In the diagram on the right, the 2 black circles (marked with two arrows) surrounding the large green sphere represent which of the following (choose all that apply)?

1.Electron energy levels 2 Electron shells

Which of the following occurs because solid water is less dense than liquid water (choose all that apply)?

-Bodies of water freeze from the top down. -Aquatic organisms can survive in liquid water below the frozen surface of ponds and lakes. -Ice floats.

If you dissolve 0.05 mol of sugar into 100 ml of water, the result is which of the following?

0.5 M solution of sugar

Substances that attract water are called ("water-loving")__________ while substances that repel water are called ("water-fearing")._______

1. hydrophyllic 2. hydrophobic

Select the molecules that tend to be hydrophilic.

1. ions 2. polar molecules

How does the partial charge of a polar covalent bond compare to the unit charge of an ion?

A partial charges is far smaller than a unit of charge.

Which of the following is the strongest bond?

A triple covalent bond

Which of the following best describes the entire alkaline range of the pH scale?

Any pH value above 7

Which of the following best describes the entire acidic range of the pH scale?

Any pH value below 7

Why is solid water less dense than liquid water?

As the movement of water molecules slows down when liquid water changes to ice, hydrogen bonds form that space the molecules relatively far apart.

Why does water have very high specific heat?

Because a large input of thermal energy is required to break the many hydrogen bonds between individual water molecules

When an acid is added to the blood, how does the carbonic acid/bicarbonate buffer work to stabilize pH?

Bicarbonate removes H+ from the blood.

Which property of water is best illustrated by this diagram?

Capillary action

When a base is added to the blood, how does the carbonic acid/bicarbonate buffer work to stabilize pH?

Carbonic acid releases H+ into the blood.

How do ions in a crystal matrix interact?

Each ion is attracted to all of the oppositely charged ions in its vicinity

In order for an electron to move to a more distal orbital which of the following must occur?

Energy must be added

Of the following list of bonds and interactions, which one is the weakest?

Hydrophobic interaction

Deficiency for which trace element can lead to an enlargement of the thyroid gland and the formation of a goiter?

Iodine

A group of atoms held together by chemical bonds in a stable association is called which of the following?

Molecule

Isotopes are atoms of the same element that differ in the number of which of the following?

Neutrons

A single water molecule can spontaneously break apart (ionize) to form which of the following?

One positive hydrogen ion and one negative hydroxide ion

When the pH of a solution rises by 1 which of the following happens?

The [H+] decreases 10-fold

The molecule shown in these two diagrams is held together by which of the following bonds?

The molecule shown in these two diagrams is held together by which of the following bonds?

Consider two electrons. One is located in the 2s orbital of an atom and the other in a 2p orbital of the same atom. Which of the following statements about those two electrons is true?

They have the same potential energy.

Which of the following explains why water rises inside a capillary glass tube?

Water molecules adhere to the surface of the glass.

How is the arrangement of water molecules related to its density?

Water molecules in ice are locked into a crystal-like lattice due to hydrogen bonds, making ice less dense than liquid.

The crystal of the ionic compound NaCl is composed of

a matrix of ions with a precise geometry.

What does it mean when we say water is adhesive?

it is attracted to other polar molecules and ions