Bonding

Question 1

Place the following in order from highest to lowest boiling point and explain why: ethanol, hexane, water, octane

Answer 1

Highest BP: Water Ethanol Octane Lowest BP: Hexane Boiling point is largely determined by intermolecular forces such as hydrogen bonding and London-dispersion forces. Water contains two sites of hydrogen bond donation as well as acceptance, so it will have the highest boiling point of the options provided. Ethanol is much smaller than octane but its ability to hydrogen bond will mean its boiling point is higher than both octane and hexane. Octane and hexane have the same weak intermolecular forces but because octane is larger, it will have the higher boiling point, as increased intermolecular interactions will require more heat energy to break.

Question 2

When determining relative boiling and melting point, what properties of a substance should you consider first?

Answer 2

Intermolecular interactions- intermolecular interactions determine boiling and melting points. The more intermolecular interactions between molecules, the higher the BP. Water has a pretty high BP when compared to a completely non polar molecule.

Question 3

Which are stronger- inter or intramolecular forces?

Answer 3

intra

Question 4

Place the following intermolecular interactions in order from strongest to weakest: H-bonds, Ion-Dipole, Dipole-dipole, Ionic, london dispersion

Answer 4

Strongest: Ionic, ion-dipole H-bonds dipole-dipole London

Question 5

Nitrate

Answer 5

NO3 -1

Question 6

Nitrite

Answer 6

NO2 -1

Question 7

Carbonate

Answer 7

CO3 -2

Question 8

Bicarbonate

Answer 8

HCO3 -1

Question 9

Perchlorate

Answer 9

ClO4 -1

Question 10

Chlorate

Answer 10

ClO3 -1

Question 11

Sulfate

Answer 11

SO4 -2

Question 12

Sulfite

Answer 12

SO3 -2

Question 13

Hydroxide

Answer 13

OH-

Question 14

Chromate

Answer 14

CrO4 2-

Question 15

Cyanide

Answer 15

CN-

Question 16

Permagnate

Answer 16

MnO4 -1

Question 17

Acetate

Answer 17

C2H3O2 -1

Question 18

If the electronegativity difference between two atoms in a bond is less than 0.5, how would you classify it? Polar, nonpolar, or ionic?

Answer 18

Nonpolar

Question 19

If the electronegativity difference between two atoms between 0.5 and 1.7, how would you classify it? Polar, nonpolar, or ionic?

Answer 19

polar

Question 20

If the electronegativity difference between two atoms in a bond is greater than 1.7, how would you classify it? Polar, nonpolar, or ionic?

Answer 20

ionic

Question 21

When naming ionic compounds, what are the general rules to remember?

Answer 21

-No prefixes -ends in “ide” -Trans metals use roman numerals -CaF2 is not calcium difluoride, its just calcium fluoride -name starts with cation

Question 22

when naming covalent compounds, what are the general rules of thumb?

Answer 22

-Element names go in order of electronegativity unless it has carbon. Carbon is always first lol. -“ide” ending but they do use prefixes: mono, di, tri, tetra, penta -The only time when you don’t use prefix is when it is a mono and it is the first element like CO is not monocarbon monoxide, its just carbon monoxide

Question 23

A mobile phase containing various solutes is run through a stationary phase containing crystals with amine (-NH2) groups. What groups would elute first and last and why?

Answer 23

Nonpolar solutes would be eluted first due to their weak interactions with the amine groups in the stationary phase. Polar protic solutes would be eluted last due to hydrogen bonding with the amine groups, and polar aprotic solutes would be eluted in the middle of the process. Note that “protic” simply references a solvent’s ability to hydrogen bond.

Question 25

Polar or Nonpolar: C-H

Answer 25

Nonpolar covalent bond

Question 26

Polar or Nonpolar: C-O

Answer 26

Polar covalent

Question 27

Polar or Nonpolar: O-H

Answer 27

Polar covalent

Question 28

What is a coordinate covalent bond?

Answer 28

A coordinate covalent bond, also known as a dative bond, dipolar bond, or coordinate bond is a kind of two-center, two-electron covalent bond in which the two electrons derive from the same atom. One atom donates both electrons.

Question 29

Hemoglobin binds several molecules, leading to a conformational change of the protein. Of the molecules that hemoglobin binds, which is the LEAST polar?

NO

CO2

CO

2,3-BPG

Answer 29

Carbon dioxide

While carbon dioxide is comprised of two oxygen atoms that are much more electronegative than carbon, the molecule is linear, which makes it nonpolar.