Download Melting and Boiling Points Questions Chemistry 2 points (1 for

Melting and Boiling Points Questions
Chemistry
2 points (1 for questions, 1 for graph)
Answer the questions on a sheet of lined paper. When you are done, staple your graph paper to your lined
paper and turn them both in.
1.
Make a line graph of the following Group 16 data (Boiling Point vs. Period):
- use graph paper to make a horizontal graph as big as the paper (no tiny graphs!)
- connect the compounds from each group of data with a separate line
x-axis: Period (from 1 to 6)
y-axis: Boiling Point (from -100 °C to +120 °C)
Group
16
2.
Compound
Molar Mass (g)
Boiling Point (°C)
2
H2O
18
100
3
H2S
34
-60
4
H2Se
81
-41
5
H2Te
129
-2
Now add the Group 17 data below to the graph, connecting these new points with a different line:
Group
17
3.
4.
5.
6.
Period
Period
Compound
Molar Mass (g)
Boiling Point (°C)
2
HF
20
19
3
HCl
36
-85
4
HBr
81
-67
5
HI
128
-35
7.
Are these chemicals in the two charts polar or nonpolar? Explain your answer.
What is the relationship between period and boiling point? (direct/indirect) Explain.
Which molecules do not follow this relationship?
What is different about these molecules that they don’t follow the same relationship?
(Hint: Think intermolecular forces!)
Looking at the data, what is the relationship between boiling point and molar mass?
8.
Read the following chart and answer the questions below:
Substance
Molar Mass (g)
Melting Point (°C)
Boiling Point (°C)
F2
38
-220
-188
Cl2
71
-101
-35
Br2
160
-7
59
I2
(a)
(b)
(c)
(d)
(e)
(f)
254
114
184
What periodic family do F2, Cl2, Br2, and I2 belong to?
What is the relationship between molar mass and boiling point within a family?
What type of intramolecular bonds are within an F2 molecule?
What type of intermolecular forces are between F2 molecules?
Melting is the change from _____ to _____. Boiling is the change from _____ to _____.
Room temperature is 25 °C. Which of the substances in the table above would be solids at
room temperature? How can you tell?
(g)
9.
Which of the substances in the table above would be liquids at room temperature?
Read the following chart and answer the questions below:
Chemical
Formula
Molar Mass (g)
Boiling Point (°C)
methane
CH4
16
-162
ethane
C2H6
30
-89
propane
C3H8
44
-42
butane
C4H10
131
(a)
What type of intramolecular bonds do these compounds have?
(b)
What intermolecular forces hold these chemicals together?
(c)
What is the relationship between number of carbons and molar mass?
(d)
What is the relationship between molar mass and boiling point?
10.
Read the following chart and answer the questions below:
Chemical
Formula
Molar Mass (g)
Boiling Point (°C)
acetone
CH3COCH3
58
56
ethyl alcohol
C2H5OH
46
78
hexane
C6H14
86
68
methyl alcohol
CH3OH
32
65
2-propyl alcohol
C3H7OH
60
83
(a)
(b)
(c)
(d)
(e)
(f)
(g)
11.
0
water
H2O
18
100
Which chemicals have the lowest and highest boiling points?
List if each chemical is polar or nonpolar. (See lab handout for structures.)
List the type of intermolecular forces holding each chemical together.
Which chemical should have evaporated the fastest during lab?
Which chemical should have evaporated the slowest during lab?
With the alcohols, what is the relationship between number of carbons and molar mass?
With the alcohols, what is the relationship between molar mass and boiling point?
Use the following chart to answer the questions below:
Substance
Intermolecular
Force
Melting Point
(°C)
Substance
Intermolecular
Force
Melting Point
(°C)
MgF2
ionic bond
1248
HBr
dipole-dipole
-89
KF
ionic bond
860
HCl
dipole-dipole
-115
NaCl
ionic bond
801
C5H12
dispersion
-130
H2O
hydrogen bond
0
CH4
dispersion
-182
NH3
hydrogen bond
- 78
H2
dispersion
-259
HF
(a)
(b)
(c)
hydrogen bond
- 83
He
dispersion
-269
Which intermolecular force appears to be the hardest to overcome with heat? Why?
Which intermolecular force appears to be the easiest to overcome with heat? Why?
Write a list of intermolecular forces from strongest to weakest.