(Prelim) Exp 2&3 Post-LAB

Question 1

It is the range of temperature at which the solid phase changes to liquid.

Answer 1

Melting Point

Question 2

It is the temperature at which the thermal motion of the molecules is just enough to break down the lattice structure of the crystal

Answer 2

Melting Point

Question 3

have sharp melting point because of the symmetry in structure and
in strength of bonds.

Answer 3

Crystal solids

Question 3

have sharp melting point and this physical property can be used to determine purity or presence of impurities.

Answer 3

Pure compounds

Question 3

It provides a means of testing for the identity of two solids by examination of the melting
point behavior of a mechanical mixture of the two

Answer 3

Mixed melting points method

Question 4

It is valuable at certain points for the identification of unknowns.

Answer 4

Mixed melting points method

Question 5

the larger the molecule, the higher the melting point.

Answer 5

For alkanes

Question 5

the more ordered the molecule, the more energy is required to break the intermolecular
forces holding the molecules together.

Answer 5

For solids

Question 6

have a lower trend in melting points than even-numbered alkanes because even-
numbered pack well in the solid phase, forming a well-organized structure.

Answer 6

Odd number alkanes

Question 6

have higher melting points compared to non-planar hydrocarbons with similar molecular weights

Answer 6

Flat shape aromatic compounds

Question 7

In the periodic table, melting point decreases

Answer 7

from center going to the sides (left and right); decrease from top to bottom.

Question 8

have very high melting points

Answer 8

Ionic compounds

Question 9

Presence of polar and hydrogen-bonding groups on organic compounds generally leads to _____________

Answer 9

higher melting points

Question 10

Oxalic acid

Answer 10

MW: 90
MP: 102

Question 11

Naphthalene

Answer 11

MW:128
MP: 80.26

Question 12

Benzoic acid

Answer 12

MW: 122
MP: 122

Question 13

Malic acid

Answer 13

MW: 134
MP: 130

Question 14

Urea

Answer 14

MW: 60
MP: 133

Question 15

Salicylic acid

Answer 15

MW: 138
MP: 158.6

Question 16

Succinic acid

Answer 16

MW: 118
MP: 184

Question 17

Apparatus used to measure melting point:

Answer 17

• Thomas-Hoover Uni-melt melting point apparatus
• Thiele tube melting point apparatus
• Fisher-johns melting point apparatus
• Nalge-axelrod melting point apparatus
• Stuart melting point apparatus SMP10

Question 17

p-amino benzoic acid

Answer 17

MW: 137
MP: 187

Question 18

It is the temperature in which the vapor pressure is equal to the atmospheric pressure.

Answer 18

Boiling Point

Question 18

Sodium benzoate

Answer 18

MW: 144
MP: 410

Question 19

It can give information about their physical properties and structural characteristics of compounds.

Answer 19

Boiling Point

Question 20

It can also be used identify and characterize compounds.

Answer 20

Boiling Point

Question 21

Just like melting point, the relative strength of intermolecular forces can affect ________

Answer 21

boiling point of compounds

Question 21

It is dependent on the kinetic energy of particles and varies with the surrounding atmospheric pressure

Answer 21

Boiling Point

Question 22

Presence of polar and hydroxyl groups can increase ______________

Answer 22

boiling point of compounds.

Question 23

As the length of ________ increases, the boiling point also increases

Answer 23

carbon chain

Question 24

Increase in the length of the carbon chain increases surface area of the compound while branching of molecules __________ the surface area.

Answer 24

decreases

Question 25

_________________ boil higher than secondary and tertiary alcohols.

Answer 25

Primary alcohols

Question 26

Acetic acid

Answer 26

MW: 60 BP: 118

Question 27

N-hexane

Answer 27

MW: 86 BP: 68.6

Question 28

N-pentane

Answer 28

MW: 72 BP: 36.1

Question 29

N-butyl alcohol

Answer 29

MW: 74 BP: 117.7

Question 30

Sec-butyl alcohol

Answer 30

MW: 144 BP: 112

Question 31

Tert-butyl alcohol

Answer 31

MW: 74 BP: 82.2