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Review Questions for Test I - General Chemistry II | CHEM 209, Exams of Chemistry

Material Type: Exam; Professor: DiLella; Class: General Chemistry II; Subject: Chemistry; University: Shepherd University; Term: Unknown 1989;

Typology: Exams

Pre 2010

Uploaded on 08/18/2009

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Chem 209 Review questions for test 1
a. Moles of solute per liter of solution is the definition of
mole fraction molarity molality parts per million
b. Which one of the following does NOT usually increase with temperature?
osmotic pressure solubility of a gas in water
vapor pressure solubility of a salt in water
c. Which one of the following forces is most important for the solubility of octane in hexane?
hydrogen bonding ion-dipole forces dipole-dipole forces London forces
d. If an aqueous solution has a boiling point of 101.00 oC at 1 atm, what is its freezing point?
( for water Kf = 1.86 oC m, Kb = 0.512 oC m)
1.86 oC 3.63 oC - 1.86 oC- 3.63 o
C
e. Which one of the following is most likely to be soluble in a nonpolar solvent?
H2O CH3OH Cl2KCl
f. Which one of the following is likely to be most soluble in H2O?
CH3OH CH3CH2CH2OH I2CH3CH2CH3
g. Which one of the following will always DECREASE the amount of O2 dissolved in water?
increasing the temperature and increasing the pressure of O2 above the water
increasing the temperature and decreasing the pressure of O2 above the water
decreasing the temperature and increasing the pressure of O 2 above the water
decreasing the temperature and decreasing the pressure of O2 above the water
h. Which one of the following statements is TRUE?
All salts easily dissolve in water
Energy is always required to break the bonds in an ionic crystal
When NaCl dissolves it breaks down into Na and Cl atoms
Salts dissolve readily in CH3CH2CH2CH2CH2CH3
i. A colligative property is a property of a solvent that
depends on the molecular weight of the solvent,
depends on the amount of solute
depends on the total mass of the solvent
depends on the volume of the solution
j. If two salt solutions are separated by a semipermeable membrane there will be a net flow of
solvent from the low concentration solution to the high concentration solution
solute from the high concentration solution to the low concentration solution
solvent from the high concentration solution to the low concentration solution
solute from the low concentration solution to the high concentration solution
k. The vapor pressure of a liquid decreases when
temperature increases
a nonvolatile solute is dissolved
the pressure above the solution is lowered
the liquid is transferred to a smaller container
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Download Review Questions for Test I - General Chemistry II | CHEM 209 and more Exams Chemistry in PDF only on Docsity!

a. Moles of solute per liter of solution is the definition of

mole fraction molarity molality parts per million

b. Which one of the following does NOT usually increase with temperature?

osmotic pressure solubility of a gas in water

vapor pressure solubility of a salt in water

c. Which one of the following forces is most important for the solubility of octane in hexane?

hydrogen bonding ion-dipole forces dipole-dipole forces London forces

d. If an aqueous solution has a boiling point of 101.

o

C at 1 atm, what is its freezing point?

( for water K f

o

C m



, K

b

o

C m



o

C 3.

o

C - 1.

o

C - 3.

o

C

e. Which one of the following is most likely to be soluble in a nonpolar solvent?

H

2

O CH

3

OH Cl 2

KCl

f. Which one of the following is likely to be most soluble in H 2

O?

CH

3

OH CH

3

CH

2

CH

2

OH I

2

CH

3

CH

2

CH

3

g. Which one of the following will always DECREASE the amount of O 2

dissolved in water?

increasing the temperature and increasing the pressure of O 2

above the water

increasing the temperature and decreasing the pressure of O 2

above the water

decreasing the temperature and increasing the pressure of O 2

above the water

decreasing the temperature and decreasing the pressure of O 2

above the water

h. Which one of the following statements is TRUE?

All salts easily dissolve in water

Energy is always required to break the bonds in an ionic crystal

When NaCl dissolves it breaks down into Na and Cl atoms

Salts dissolve readily in CH 3

CH

2

CH

2

CH

2

CH

2

CH

3

i. A colligative property is a property of a solvent that

depends on the molecular weight of the solvent,

depends on the amount of solute

depends on the total mass of the solvent

depends on the volume of the solution

j. If two salt solutions are separated by a semipermeable membrane there will be a net flow of

solvent from the low concentration solution to the high concentration solution

solute from the high concentration solution to the low concentration solution

solvent from the high concentration solution to the low concentration solution

solute from the low concentration solution to the high concentration solution

k. The vapor pressure of a liquid decreases when

temperature increases

a nonvolatile solute is dissolved

the pressure above the solution is lowered

the liquid is transferred to a smaller container

l. A solution is made by mixing one mole of toluene with one mole of benzene at 25 C. For

pure benzene the vapor pressure is 80 torr and for pure toluene the vapor pressure is 50

torr. The mole fraction of toluene in the vapor above the solution is

greater than 0.5 equal to 0.5 less than 0.

m. Which one of following aqueous solutions will have the lowest freezing point

0.5 m NaCl 0.25 m KCl 0.2 m MgCl 2

0.1 m CoCl 3

n. Which one of the following forces is most important for the high solubility of KCl in water

hydrogen bonding London forces ion-dipole forces dipole-dipole forces

o. The solubility of a gas is water is highest for which conditions of temperature and pressure?

high P, high T high P, low T low P, high T low P, low T

p. Which one of the following is NOT a colligative property?

freezing point depression temperature

osmotic pressure vapor pressure lowering

q. Which one of the following combinations would NOT be likely form a solution

ionic solid and non-polar liquid

ionic solid and polar liquid

polar solid and polar liquid

non-polar solid and non-polar liquid

r. Blood cells have a semipermeable membrane and their fluid contains dissolved ions. When

blood cells are placed in a concentrated salt solution they shrink because

ions pass through the cell membrane by osmosis

water passes through the cell membrane by osmosis

water passes through the cell membrane by reverse osmosis

salt passes through the cell membrane by osmosis

s. Which one of the following is a colloid that has a solid suspended in a liquid?

emulsion sol foam aerosol

t. A soap molecule contains

a polar group at the end of a long polar chain

a nonpolar group at the end of a long polar chain

a nonpolar group at the end of a long nonpolar chain

a polar group at the end of a long nonpolar chain

. Which one of the following statements is TRUE?

A mixture of liquids is always a solution

A colloid is a solution

A solution may have more than one phase

Air is an example of a solution

____________________________________________________________

Circle the member of each of the following pairs that is likely to be more soluble in the indicated

solvent.

CH

3

CH

2

CH

2

OH or Br 2

CH

3

CH

2

CH

2

CH

2

CH

2

OH or CH 3

OH CH

3

OH or I 2

mol

g

0. 372 mol

1000 g

20 g

2 .15 g

unk

CCl 4

CCl 4

unk

_________________________________________________

3 A solution is made by adding 10.0 g of NaCl (FW = 58.4 g mol



 to 100.0 g of H 2

O (MW =

18.0 g mol



). The vapor pressure of pure H 2

O is 18 torr at 20 C.

a. Find the vapor pressure of the solution at 20 C.

  1. 172 mol

5 8.4g mol

1 0.0 g

n

1

NaCl

  1. 51 mol

18 g mol

100 g

n

1

H 2 O

  1. 51 mol 0 .. 172 mol

  2. 51 mol

x

H 2 O

P x P 0. 970  1 8.0mmHg 17. 5 mmHg

0

H 2 O H 2 O H 2 O

b. Find the freezing point of this solution. (K f

= 1.86 C/m for water)

  1. 72 m

kg

mol

  1. 72

  2. 100 kg

  3. 172 mol

molality   

T iKm 2  1. 86 Cm  1. 72 m 6. 40 C

o 1 o

f f

freezing point = 0 – T f

o

C

__________________________________________________________

Calculate the osmotic pressure in torr for a 650 mL of an aqueous solution containing 42.0 g of

sucrose. Assume the temperature is 25 C. (MW = 342 g/mol for sucrose)

  1. 123 mol

342 g mol

  1. 0 g

1

L

mol

0. 650 L

  1. 123 mol

M  

0. 0821 LatmK mol  298 K 4. 63 atm

L

mol

MRT 0. 189

1 1

 

__________________________________________________________________________

7 (10) Find the osmotic pressure in torr for a solution made by adding 20.0 g of NaCl (FW 58.44)

to 200 mL of water. Assume the temperature is 20

o

C.

L

mol

0. 200 L

  1. 342 mol

200 mL

  1. 44 g mol

  2. 0 g

V

n

M

1

 = iMRT

   293 K 82. 4 atm

mol K

  1. 0821 L atm

L

mol

  6. 26 10 torr

atm

760 torr

  1. 4 atm

4

___________________________________________________________________________

Assume that the partial pressure of O 2

above a solution is 150 mm Hg and the partial pressure of

N

2

is 610 mm Hg. For water at 20

o

C, the Henry’s law constant for O 2

is 1.43 x

mol L

atm

and for N 2

is 7.34x

mol L

atm

What is the molarity of O 2

in solution?

What is the mole fraction of O 2

in solution? Assume that the density of water is 1.

g/mL. FW O 2

= 18 g/mol, FW H2O = 18 g/mol.

Is there more N 2

or O 2

dissolved in the water? Show calculations to demonstrate your

conclusion.

___________________________________________________________________________

a. Which one of the following DOES NOT have cis and trans isomers?

2,3-dichloro-2-butene 1,1-dichloro-1-butene

2-chloro-2-butene 1,2-dichloro-propene

b Which one of the following molecules could be used to make a chain growth (addition)

polymer?

methanol propene methyl ethyl ether ethane

c. Which one of the followings statements is FALSE?

Proteins are made up from amino acids linked together by condensation reactions

The genetic code is stored in the sequence of the bases in DNA

The -helix is an important structure for proteins

A nucleotide contains phosphate group, an ether and an organic base

d. Which one of the following compounds is a saturated hydrocarbon?

4-Pentene 2-butyne 3-methyl 2-pentene 2-methylpropane

e. How many isomers are there for the formula C 2

H

2

Cl 2

f. Which one of the following is a polysaccharide that is used to store energy in the human body

fructose starch glucose cellulose

g. Which one of the following is not part of DNA?

phosphate base sugar amino acid

h. Which one of the bonds in the DNA double helix structure are the weakest

the bonds between the bases

the bonds between the phosphate and sugar

the bond between the sugar and the base

the bond between the base and phosphate

i. How many isomers are there for the formula C 3

H

6

Br 2

__________________________________________________________

Draw the structures of the following.

3-pentanol 2-hexanone 2,6-dimethyl-3-heptene

3-methyl butanal 2,2,4-trimethylpentane

C

C

C

C

C

C

C

C C

C

C

C

C

C

C

C C

C C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C C

C C

C

C C

C C

C

C

C

C

C

C

C

C

C

C

C

C

C C

C

1-pentene trans 2-pentene

cis 2-pentene

cyclopentane methyl cyclobutane

ethyl cyclopropane

2-methyl 2 butene

3 methyl 1 butene

2 methyl 1 butene

trans 1,2-dimethyl

cyclopropane

cis 1,2-dimethyl

cyclopropane

1,1-dimethyl

cyclopropane

H

3

C

CH

2

CH

CH

2

CH

3

OH

H

3

C C CH

2

CH

2

CH

2

CH

3

O

H

3

C

C

CH

CH

2

CH

2

CH

CH

3

H

3

C CH 3

C

CH

2

CH

CH

3

CH

3

O

H

H

3

C C CH

2

CH CH

3

CH 3

CH

3

CH 3

  1. (5 pts) Identify the class (alcohol, alkane, alkene, alkyne, amine, amide, amino acid, aldehyde,

aromatic, carboxylic acid, ether, ester, ketone) that best describes the following molecules. R and

R’ are hydrocarbon groups

alcohol amine aldehyde acid ketone

Identify each of the four following structures as (amino acid, alkane, alkyne, alkene, aromatic,

carbohydrate, dipeptide, dissacharide, nucleotide, tripeptide)

nucleotide carbohydrate

dipeptide amino acid

Consider the molecule shown below. Use asterisks to indicate the chiral carbons.

N

H

N

H

C

O

C

C

O

O

C

H

H

O H

C H

3

C

O H

H

H

C

O H

N

C H

3

Draw the structures for four compounds with the formula C 4

H

8

. Name all compounds. (1 point

per correct structure, 1 point per correct name, 8 points max)

H 2

C

H 2

C CH 2

CH 2

C C

H

CH 3

H

3

C

H

C C

H

CH 3

H

H 3

C

C C

CH 3

CH

3

H

H

trans-2-butene

cis-2-butene

2-methylpropene cyclobutane