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Chemistry Test 4 for Fall 2006 - Prof. James B. Condon, Exams of Chemistry

A chemistry test for the fall of 2006, including multiple-choice questions on topics such as van't hoff factor, molality, vapor pressure, osmotic pressure, freezing point depression, boiling point elevation, intermolecular forces, and phase diagrams. It also includes an answer sheet for the test.

Typology: Exams

Pre 2010

Uploaded on 08/18/2009

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CHEM 1110 test 4 for fall 2006 Page 1
Circle the correct answer on the answer sheet.
H
e
v
RT
PA
Δ
⎛⎞
⎜⎟
⎝⎠
=
1
212
H11
ln v
P
PRTT
⎛⎞
Δ
⎛⎞
=−
⎜⎟
⎜⎟
⎝⎠
⎝⎠
R = 8.314 J mol–1 K–1 R = 0.08206 L atm mol–1 K–1
If the a compound does not ionize in solution, the “effective approximate” van’t Hoff factor is 1.
Temperature in EC versus Water Vapor Pressure in torr
0EC 4.6 torr 10EC 9.2 torr 20EC 17.5 torr 30EC 31.8 torr 40EC 55.3 torr
1EC 4.9 torr 11EC 9.8 torr 21EC 18.7 torr 31EC 33.7 torr 41EC 58.3 torr
2EC 5.3 torr 12EC 10.5 torr 22EC 19.8 torr 32EC 35.7 torr 42EC 61.5 torr
3EC 5.7 torr 13EC 11.2 torr 23EC 21.1 torr 33EC 37.7 torr 43EC 64.8 torr
4EC 6.1 torr 14EC 12.0 torr 24EC 22.4 torr 34EC 39.9 torr 44EC 68.3 torr
5EC 6.5 torr 15EC 12.8 torr 25EC 23.8 torr 35EC 42.2 torr 45EC 71.9 torr
6EC 7.0 torr 16EC 13.6 torr 26EC 25.2 torr 36EC 44.6 torr 46EC 75.7 torr
7EC 7.5 torr 17EC 14.5 torr 27EC 26.7 torr 37EC 47.1 torr 47EC 79.6 torr
8EC 8.0 torr 18EC 15.5 torr 28EC 28.3 torr 38EC 49.7 torr 48EC 83.7 torr
9EC 8.6 torr 19EC 16.5 torr 29EC 30.0 torr 39EC 52.4 torr 49EC 88.0 torr
1. Approximately what is the van’t Hoff factor for Sc(NO3)3?
a. 1 b. 2 c. 3 d. 4 e. 5
2. A solution consists of 5.00 g of methanol (CH3OH molar mass = 32.0 g mol–1) and 400 g of
water. What is the total molality of the solute?
a. 1.28 mol kg–1 b. 0.782 mol kg–1 c. 2.56 mol kg–1 d. 0.125 mol kg–1 e. 0.391 mol kg–1
3. A solution consists of 35.5 g of FeCl3 (molar mass = 162.2 g mol–1) in 350 g of water. What
is the total molality of the solute?
a. 0.200 mol kg–1 b. 2.50 mol kg–1 c.1.60 mol kg–1 d. 0.800 mol kg–1 e. 0.400 mol kg–1
pf3
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Download Chemistry Test 4 for Fall 2006 - Prof. James B. Condon and more Exams Chemistry in PDF only on Docsity!

Circle the correct answer on the answer sheet.

H

e

v RT

P A

−⎛^ Δ ⎞ ⎜⎝ ⎟⎠

1 2 1 2

H 1

ln v

P

P R T T

⎜ ⎟ = −^ ⎜ ⎟⎜ − ⎟

⎝ ⎠ ⎝^ ⎠⎝ ⎠

R = 8.314 J mol –1^ K–1^ R = 0.08206 L atm mol –1^ K–

If the a compound does not ionize in solution, the “effective approximate” van’t Hoff factor is 1.

Temperature in EC versus Water Vapor Pressure in torr 0 EC 4.6 torr 10 EC 9.2 torr 20 EC 17.5 torr 30 EC 31.8 torr 40 EC 55.3 torr 1 EC 4.9 torr 11 EC 9.8 torr 21 EC 18.7 torr 31 EC 33.7 torr 41 EC 58.3 torr 2 EC 5.3 torr 12 EC 10.5 torr 22 EC 19.8 torr 32 EC 35.7 torr 42 EC 61.5 torr 3 EC 5.7 torr 13 EC 11.2 torr 23 EC 21.1 torr 33 EC 37.7 torr 43 EC 64.8 torr 4 EC 6.1 torr 14 EC 12.0 torr 24 EC 22.4 torr 34 EC 39.9 torr 44 EC 68.3 torr 5 EC 6.5 torr 15 EC 12.8 torr 25 EC 23.8 torr 35 EC 42.2 torr 45 EC 71.9 torr 6 EC 7.0 torr 16 EC 13.6 torr 26 EC 25.2 torr 36 EC 44.6 torr 46 EC 75.7 torr 7 EC 7.5 torr 17 EC 14.5 torr 27 EC 26.7 torr 37 EC 47.1 torr 47 EC 79.6 torr 8 EC 8.0 torr 18 EC 15.5 torr 28 EC 28.3 torr 38 EC 49.7 torr 48 EC 83.7 torr 9 EC 8.6 torr 19 EC 16.5 torr 29 EC 30.0 torr 39 EC 52.4 torr 49 EC 88.0 torr

  1. Approximately what is the van’t Hoff factor for Sc(NO 3 ) 3?

a. 1 b. 2 c. 3 d. 4 e. 5

  1. A solution consists of 5.00 g of methanol (CH 3 OH molar mass = 32.0 g mol –1) and 400 g of water. What is the total molality of the solute?

a. 1.28 mol kg–1^ b. 0.782 mol kg–1^ c. 2.56 mol kg–1^ d. 0.125 mol kg–1^ e. 0.391 mol kg–

  1. A solution consists of 35.5 g of FeCl 3 (molar mass = 162.2 g mol –1) in 350 g of water. What is the total molality of the solute?

a. 0.200 mol kg–1^ b. 2.50 mol kg–1^ c.1.60 mol kg–1^ d. 0.800 mol kg–1^ e. 0.400 mol kg–

  1. What is the vapor pressure of water at 40EC over a solution that has 10.0 g of ethanol (molar mass = 46.0 g mol –1^ ) for every 100 g of water?

a. 0.962 torr b. 731 torr c. 49.8 torr d. 53.2 torr e. 2.10 torr

  1. What is the osmotic pressure for a solution at 25EC which is 1.0 M formally in CaCl 2?

a. 24.4 atm b. 48.9 atm c. 73.4 atm d. 2478 atm e. 7433 atm

  1. The Kf for benzene is 8.0 K kg mol –1. What would be the freezing point lowering if 6.0 g of hexane (C 6 H 14 molar mass of 86.0 g mol –1) is dissolved in 100.0 g of benzene?

a. 11.2 K b. 2.79 K c. 5.58 K d. 0.48 K e. 0.60 K

  1. Which of the following molecules has a dipole moment?

a. CH 4 b. PF 5 c. SO 3 d. SO 2 e. CO 2

  1. All of the following compound except one will hydrogen bond with itself. Which one of the following molecules cannot hydrogen bond to an identical molecule?

a. H 2 O b. H 3 CNH 2 c. H 3 COCH 3 d. HF e. CH 3 COOH

  1. Which of the following compounds forms a liquid due only to London forces?

a. CH 3 F b. KCl c. HCl d. SF 6 e. H 2 O

  1. Calculate the molar mass of an unknown non-electrolyte if 1.745 g of it dissolved in 32.5 g of water lowers the freezing point of the water by 3.12EC. The Kf for water is 1.86EK kg mol –^.

a. 3.0 g mol –1^ b. 84.0 g mol –1^ c. 60.0 g mol –1^ d. 0.0313 g mol –1^ e. 32.0 g mol –

  1. The solid compound consisting only of magnesium is classified as what type of solid?

a. ionic solid b. covalent solid c. metallic solid d. molecular solid e. London solid

  1. What are the strongest intermolecular forces that is responsible for water being a liquid?

a. ionic-ionic attractions b. London forces c. covalent forces d. dipole-dipole attractions e. hydrogen bonding

  1. Which one of the following is the sequence of boiling points from the lowest to highest for the noble gas series? (lowest < < < highest)

a. Xe < Ne < Ar < Kr < He b. He < Ne < Ar < Kr < Xe c. Ar < He < Ne < Kr < Xe d. He < Kr < Ar < Ne < Xe e. He < Ne < Ar < Kr < Xe

  1. The Kf for a solvent is 3.50 K kg mol –1. When 15.0 g of a non-electrolyte is dissolve in some of this solvent the freezing point depression was 1.55 K and the boiling point elevation was 1.15 K. What is the Kb in units of K kg mol –1^ for this solvent?

a. 2.60 b. 4.72 c. 3.50 d. 3.15 e. indeterminate

  1. What is the approximate van’t Hoff factor for CH 3 CH 2 OH?

a. 2 b. 1 c. 3 d. 7 e. 9

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Answer sheet - circle the correct letter for the answer

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