Download Chemistry 100 Second Homework

Chemistry 110 – 02
Winter 2017
Ninth Homework
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Study Hill and McCreary Chapter 6 sections 3 – 4.
Study Hill and McCreary Chapter 7 sections 1, 2, and 4 - 6.
Begin reviewing for the final exam by reworking past homework and quiz questions.
Review memorized information like compound names, formulas for ions, etc.
Quiz 7 will include questions from the information and questions below and from the Tenth
Homework. To be prepared for the quiz, you should be able to answer these questions using only
the periodic table you received in class and the information given. Any quiz may include questions
about lab safety and procedures.
Due 7:30 am Wednesday, March 1. 10 Points.
Late homework is not accepted after 8:30 am Thursday, March 2.
1. Predict what types of intermolecular attractions are present in each of these pure compounds.
a. ethane (CH3CH3)
b. octane (CH3CH2CH2CH2CH2CH2CH2CH3)
O
CH3 )
c. acetone (H3C C
d. propanol (CH3CH2CH2OH)
e. dichloromethane (CH2Cl2)
2. For each of these compounds, indicate what types of intermolecular attractions are present
between the molecules of the pure compound.
a. ethane (CH3CH3)
b. chloromethane (CH3Cl)
c. formaldehyde (H2CO)
d. methanol (CH3OH)
e. octanol (CH3CH2CH2CH2CH2CH2CH2CH2OH)
3. Predict which compound in each pair will have the stronger intermolecular attractions in the
pure substance.
a. ethane (CH3CH3) or octane (CH3CH2CH2CH2CH2CH2CH2CH3)
O
CH3 ) or propanol (CH CH CH OH)
b. acetone (H3C C
3
2
2
c. methane (CH4) or dichloromethane (CH2Cl2)
d. dichloromethane (CH2Cl2) or propane (CH3CH2CH3)
4. Predict which compound in each pair has the higher heat of vaporization.
a. ethane (CH3CH3) or octane (CH3CH2CH2CH2CH2CH2CH2CH3)
O
CH3 ) or propanol (CH CH CH OH)
b. acetone (H3C C
3
2
2
c. methane (CH4) or dichloromethane (CH2Cl2)
d. dichloromethane (CH2Cl2) or propane (CH3CH2CH3)
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5. Predict which compound in each pair has the higher boiling point.
a. ethane (CH3CH3) or octane (CH3CH2CH2CH2CH2CH2CH2CH3)
O
CH3 ) or propanol (CH CH CH OH)
b. acetone (H3C C
3
2
2
c. methane (CH4) or dichloromethane (CH2Cl2)
d. dichloromethane (CH2Cl2) or propane (CH3CH2CH3)
6. Run the Intermolecular Attractions and Melting Point simulation on the class web page.
Explore how the strength of the intermolecular attractions affects the melting temperature. (Set
the Intermolecular Attractions to weak and find the temperature at which the solid melts. Repeat
with the Intermolecular Attractions set to medium and strong.) What is the relationship between
the strength of the intermolecular attractions and the melting temperature?
7. Draw a water molecule. Now draw four more water molecules around this first molecule,
showing the arrangement of the molecules. Use dashed lines to show the hydrogen bonding
attractions between the first molecule and the four surrounding molecules.
8. A drop of liquid water evaporates (becomes gas).
a. Sketch what the liquid looks like at the nanoscale. Show any hydrogen bonding attractions.
b. Sketch what the gas looks like at the nanoscale. Show any hydrogen bonding attractions.
(You might run the States of Matter – Molecular simulation to help with this. Increase the
temperature so the sample is a gas.) Remember that intermolecular attractions are present only
when the molecules are right next to each other.
9. Distilled water is very expensive because it takes a large amount of energy to convert liquid
water at 100 °C into gaseous water (steam) at 100 °C. This energy is called the heat of
vaporization. Explain what is happening at the nanoscale when liquid water becomes gaseous
water and why this change requires a large amount of energy in water. (You might run the
States of Matter – Molecular simulation to help with this.)
10 For each of these compounds, indicate what types of intermolecular attractions are present
between the molecule listed and water molecules.
a. between ethane (CH3CH3) and water
b. between chloromethane (CH3Cl) and water
c. between formaldehyde (H2CO) and water
d. between methanol (CH3OH) and water
e. between octanol (CH3CH2CH2CH2CH2CH2CH2CH2OH) and water
f. between acetone (CH3COCH3, the 3 carbon atoms are bonded together. The oxygen is
double bonded to the central carbon.) and water
11. For each of these compounds, indicate whether it should be very soluble in water or not soluble.
a. ethane (CH3CH3)
b. chloromethane (CH3Cl)
c. formaldehyde (H2CO)
d. methanol (CH3OH) e. octanol (CH3CH2CH2CH2CH2CH2CH2CH2OH)
f. acetone (CH3COCH3, the 3 carbon atoms are bonded together. The oxygen is double bonded
to the central carbon.)
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12. Proteins are made by creating covalent bonds between many amino acid molecules. In a protein,
the amino acids are bonded in one long chain. One part of each amino acid sticks out from the
chain, like charms on a charm bracelet. This part of the amino acid is called the “R group”.
What a protein does in an organism and how it works partly depends on the properties of these
R groups. One important property is the type of intermolecular attractions it has with water.
Four amino acid R groups are shown. For each, indicate whether or not the R group attracts
water via hydrogen bonding attractions.
H
a. valine:
H3C
c. phenylalanine:
b. glutamic acid:
C
O
CH3
H
H
O
H
H
C
C
C
H
H
d. threonine:
C
H
H
H
H
C
C
H
OH
13. Which of these statements are true?
a. Sometimes energy is released when a covalent bond is broken.
b. Oil molecules and water molecules repel each other when they get close together.
c. When water evaporates, it becomes hydrogen gas and oxygen gas.
d. The atoms present after a chemical reaction are the same as the atoms present before the
chemical reaction.
And constantly, I seek
A poetry of facts. Even as
The profound kinship of all living substance
Is made clear by the chemical route.
Without some chemistry one is bound to remain
Forever a dumbfounded savage
In the face of vital reactions.
The beautiful relations
Shown only by biochemistry
Replace a stupefied sense of wonder
With something more wonderful
Because natural and understandable.
Nature is more wonderful
When it is at least partly understood.
Such an understanding dawns
On the lay reader when he becomes
Acquainted with the biochemistry of the glands
In their relation to diseases such as goiter
And in their effects on growth, sex, and reproduction.
He will begin to comprehend a little
The subtlety and beauty of the action
Of enzymes, viruses, and bacteriophages,...
- from "The Kind of Poetry I Want" - Hugh MacDiarmid -
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