Q&A Hero

Q: For a dilute solution of FeCl3, the van"t Hoff factor (i) would be approximately A) 4. B) 2. C) 3. D) 1. E) 5.

Q: For a dilute solution of (NH4)3PO4, the van"t Hoff factor (i) would be approximately A) 4. B) 2. C) 3. D) 1. E) 5.

Q: To determine the molar mass of a small protein in the range of 20,000"40,000 g/mol, it would be best to measure A) the freezing point of the solvent and of the solution and the weight of the solute and solvent. B) the boiling point of the solvent and of the solution and the weight of the solute and solvent. C) the vapor pressure of the solvent and of the solution and the weight of the solute and solvent. D) the osmotic pressure of the solution and the weight of the solute and solvent. E) the density of the protein and to make x-ray measurements.

Q: Calculate the molecular weight of a small protein if a 0.24-g sample dissolved in 108 mL of water has an osmotic pressure of 9.5 mmHg at 22ºC. (R= 0.0821 L.atm/(K.mol))A) 3.2 x102g/molB) 4.3 x103g/molC) 5.7 g/molD) 1.8 x102g/molE) 5.7 x10-3g/mol

Q: Osmotic pressure is A) inversely proportional to mass fraction. B) directly proportional to lattice energy. C) inversely proportional to molality. D) inversely proportional to mole fraction. E) directly proportional to molarity.

Q: A 2.4-g sample of a small protein having a molecular weight of 62,000 g/mol is dissolved in 59.6 mL of water at 29ºC. What is the osmotic pressure of the solution? (R=0.0821L"¢atm/(K"¢mol))A) 12 mmHgB) 760 mmHgC) 1.2 mmHgD) 47,000 mmHgE) 0.016 mmHg

Q: Determine the osmotic pressure of a solution that contains 0.014 g of a hydrocarbon solute (molar mass = 340 g/mol) dissolved in benzene to make a 350-mL solution. The temperature is 20.0ºC.A) 0.9 torrB) 2.0 torrC) 0.14 torrD) 0.7 torrE) 2.1 torr

Q: A solution of water and a nonvolatile, nonionizing compound is placed in a tube with a semipermeable membrane on one side. The tube is placed in a beaker of pure water. What initial net effect will occur? A) Nothing will move through the membrane either way. B) Water will flow from the beaker to the tube. C) Water will flow from the tube to the beaker. D) Equilibrium will be immediately established. E) The compound will pass through the membrane into the solution.

Q: What is reverse osmosis? A) the application, to a dilute solution, of a pressure that is greater than the osmotic pressure, such that solvent flows from the concentrated solution to the dilute solution B) the application, to a dilute solution, of a pressure that is greater than the osmotic pressure, such that solute flows from the concentrated solution to the dilute solution C) the application, to a concentrated solution, of a pressure that is greater than the osmotic pressure, such that solute flows from the concentrated solution to the dilute solution D) the application, to a concentrated solution, of a pressure that is greater than the osmotic pressure, such that solvent flows from the concentrated solution to the dilute solution E) the application, to a concentrated solution, of a pressure that is greater than the osmotic pressure, such that solvent flows from the dilute solution to the concentrated solution

Q: A red blood cell placed in pure water will swell because A) the osmotic pressure is greater in the water than in the cell. B) the osmotic pressure is the same in the cell and the water. C) the osmotic pressure is greater in the cell than in the water. D) water moves from a higher osmotic pressure to a lower osmotic pressure. E) the vapor pressure of the water in the cell is greater than the vapor pressure of pure water.

Q: A cucumber is placed in a concentrated salt solution. What is most likely to happen? A) Water will flow from the solution to the cucumber. B) No change will occur. C) Salt will flow into the cucumber. D) Salt will precipitate out. E) Water will flow from the cucumber to the solution.

Q: A compound containing sulfur, nitrogen, and hydrogen has a composition of 86.6% sulfur, 12.6% nitrogen, and 0.91% hydrogen by mass. A solution prepared by dissolving 2.072g of this compound in 35.00 g of bromoform, CHBr3, produces a solution that freezes at 3.97ºC. What is the molecular formula of the compound? (Kf for bromoform is 14.4ºC/m, and pure bromoform has a freezing point of 7.8ºC.)A) SNHB) S3N2H2C) S6N2H2D) S3NHE) S2N2H2

Q: A compound containing carbon and nitrogen has a composition of 46.16% carbon and 53.84% nitrogen by mass. A solution prepared by dissolving 1.542 g of this compound in 30.00 g of carbon tetrachloride, CCl4, produces a solution that boils at 81.69ºC. What is the molecular formula of the compound? (Kb for CCl4 is 5.03ºC/m, and pure CCl4has a freezing point of 76.72ºC.)A) C2N2B) CN2C) C3N3D) CNE) C2N4

Q: Which of the following will cause the calculated molar mass of a compound determined by the freezing-point-depression method to be greater than the true molar mass?A) When the solute was added, some was spilled on the lab bench.B) Water gets into the solvent after the freezing point of the pure solvent is determined.C) Some of the solute molecules break apart.D) The mass of solvent is smaller than that determined from the weighing.E) all of the above

Q: What is the molar mass of an aromatic hydrocarbon if 0.85 g of the compound depresses the freezing point of 128 g of benzene by 0.37ºC? (Kffor benzene is 5.12ºC/m.)A) 35 g/molB) 150 g/molC) 93 g/mol 92D) 2100 g/molE) 140 g/mol

Q: If a 18.0-g sample of a nonelectrolyte is dissolved in 112.0 g of water, the resulting solution will freeze at -0.94ºC. What is the molar mass of the nonelectrolyte? (Kf for water is 1.858ºC/m.)A) 77 g/molB) 0.32 g/molC) 550 g/molD) 280 g/molE) 320 g/mol

Q: Thyroxine, an important hormone that controls the rate of metabolism in the body, can be isolated from the thyroid gland. If 0.453 g of thyroxine is dissolved in 10.0 g of benzene, the freezing point of the solution could be measured as 5.144ºC. Pure benzene freezes at 5.444ºC and has a value for the molal freezing-point-depression constant of Kf of 5.12ºC/m. What is the approximate molar mass of thyroxine?A) 773 g/molB) 7.73 g/molC) 7.73 x105g/molD) 42.6 g/molE) 11.3 g/mol

Q: When a 28.4-g sample of an unknown compound is dissolved in 500. g of benzene, the freezing point of the resulting solution is 3.77ºC. The freezing point of pure benzene is 5.48ºC, and Kf for benzene is 5.12ºC/m. Calculate the molar mass of the unknown compound.A) 145 g/molB) 170. g/molC) 85.0 g/molD) 340 g/molE) 16.6 g/mol

Q: Trimellitic acid is an organic acid that has a composition of 51.44% C, 2.88% H, and 45.68% O by mass. A 5.02-g sample of trimellitic acid dissolved in 20 g of acetone, CH3COCH3, has a boiling point of 58.24C. What is the molecular formula of trimellitic acid? (Kb for acetone is 1.71ºC/m, and pure acetone has a boiling point of 56.20ºC.)A) CH2OB) C9H6O6C) C3HO2D) C18HO16E) C6H2O4

Q: Which of the following methods cannot be used to determine the molar mass of a nonelectrolyte?A) measurement of the freezing-point depression of a solution of the compoundB) measurement of the boiling-point elevation of a solution of the compoundC) measurement of the pressure, temperature, volume, and mass of the compound in the gaseous stateD) measurement of the x-ray diffraction of a pure crystal of the compoundE) measurement of the osmotic pressure of a solution of the compound

Q: What is the mass percent of ethylene glycol (HOCH2CH2OH) in a solution of ethylene glycol in water that has a freezing point of -19.2ºC? (Kffor water is 1.858ºC/m.)A) 99.8%B) 39.1%C) 64.1%D) 60.1%E) 10.3%

Q: A solution consisting of 0.228 mol of methylbenzene, C6H5CH3, in 255 g of nitrobenzene, C6H5NO2, freezes at -0.3ºC. Pure nitrobenzene freezes at 6.0ºC. What is the freezing-point depression constant of nitrobenzene?A) 1.1ºC/mB) 27ºC/mC) 14.0ºC/mD) 3.5ºC/mE) 7.0ºC/m

Q: Substance A has a greater molar mass than substance B. If 50 g of substance A are dissolved in 250 g of water in one beaker, and 50 g of substance B are dissolved in 250 g of water in another beaker, then A) the vapor pressure of solution A will be lower than the vapor pressure of solutionB. B) the solution of A will freeze at a lower temperature than the solution ofB. C) the two solutions will have the same vapor pressure. D) the boiling point of solution A will be lower than the boiling point of solutionB. E) the solution of A will have a higher osmotic pressure than the solution ofB.

Q: What is the boiling-point change for a solution containing 0.432 mol of naphthalene (a nonvolatile, nonionizing compound) in 250. g of liquid benzene? (Kb= 2.53ºC/m for benzene)A) 4.37ºCB) 5.86ºCC) 0.273ºCD) 1.46ºCE) 1.093ºC

Q: What is the freezing point of a 0.24 msolution of glucose, C6H12O6, in water? (Kf for water is 1.858C/m.)A) 0.22ºCB) 0.45ºCC) -0.45ºCD) -0.22ºCE) -0.89ºC

Q: A solute added to a solvent raises the boiling point of the solution because A) the temperature to cause boiling must be great enough to boil not only the solvent but also the solute. B) the solute particles raise the solvent's vapor pressure, thus requiring a higher temperature to cause boiling. C) the solute increases the volume of the solution, and an increase in volume requires an increase in the temperature to reach the boiling point (derived from PV= nRT). D) the solute particles lower the solvent's vapor pressure, thus requiring a higher temperature to cause boiling. E) two of these explanations are correct.

Q: The fact that the boiling point of a pure solvent is lower than the boiling point of a solution of the same solvent is a direct consequence of the A) freezing-point depression of the solution. B) vapor pressure of the solution being higher than the vapor pressure of the pure solvent. C) osmotic pressure of the solvent being lower than the osmotic pressure of the solution. D) vapor pressure of the solution being lower than the vapor pressure of the pure solvent. E) osmotic pressure of the solvent being higher than the osmotic pressure of the solution.

Q: A solution of CF3H in H2CO is most likely to A) be ideal. B) not be ideal, but the deviations cannot be predicted. C) show negative deviations from Raoult's law. D) obey Raoult's law. E) show positive deviations from Raoult's law.

Q: A solution of two liquids, A and B, shows negative deviation from Raoult's law. This means that A) the two liquids have a positive heat of solution. B) molecules of A interact more strongly with B than A molecules interact with A or B molecules interact with B. C) molecules of A interact strongly with other A-type molecules. D) molecules of A interact weakly, if at all, with B molecules. E) molecules of A hinder the strong interaction between B molecules.

Q: A liquid"liquid solution is called an ideal solution ifI. it obeys PV= nRT.II. it obeys Raoult's law.III. solute-solute, solvent-solvent, and solute-solvent interactions are very similar.IV. solute-solute, solvent-solvent, and solute-solvent interactions are quite different.A) I, III, IVB) I, II, IIIC) II, III onlyD) I, II, IVE) II, IV only

Q: Benzene, C6H6, and toluene, C6H5CH3, form ideal solutions. At 35ºC the vapor pressure of benzene is 160. torr and that of toluene is 50.0 torr. In an experiment, 3.6 mol of benzene and 5.5 mol of toluene are placed in a closed container at 35ºC and allowed to come to equilibrium. What is the mole fraction of toluene in the vapor phase?A) 0.52B) 0.68C) 0.32D) 0.14E) 0.60

Q: Benzene, C6H6, and toluene, C6H5CH3, form ideal solutions. At 35ºC the vapor pressure of benzene is 160. torr and that of toluene is 50.0 torr. In an experiment, 67.6g of benzene and 86.7g of toluene are placed in a closed container at 35ºC. At equilibrium, what is the partial vapor pressure of toluene?A) 108 torrB) 83.3 torrC) 24.0 torrD) 76.7 torrE) 26.0 torr

Q: What is the vapor pressure at 75ºC of an aqueous solution prepared by the addition of 64.3g of the nonvolatile solute urea, CO(NH2)2, to 174 g of water? The vapor pressure of pure water at 75ºC is 290.mmHg.A) 133 mmHgB) 28.9 mmHgC) 167 mmHgD) 261 mmHgE) 212 mmHg

Q: What is the vapor pressure at 20ºC of an ideal solution prepared by the addition of 8.87g of the nonvolatile solute urea, CO(NH2)2, to 57.6 g of methanol, CH3OH? The vapor pressure of pure methanol at 20ºC is 89.0 mmHg.A) 6.75 mmHgB) 69.1 mmHgC) 77.1 mmHgD) 82.2 mmHgE) 19.9 mmHg

Q: When 1 mol of a nonvolatile nonelectrolyte is dissolved in 3 mol of a solvent, the vapor pressure of the solution compared with that of the pure solvent is A) 1/4. B) 4/5. C) 1/2. D) 1/5. E) 3/4.

Q: Which way of expressing concentration is used to relate the vapor pressure of a solution to the amount of nonvolatile solute dissolved in the solution? A) mole fraction B) molarity C) osmotic pressure D) mass percent E) molality

Q: What is the mole fraction of urea in a solution that contains 2.1 mol of urea and 4.4 mol of water? A) 0.77 B) 0.32 C) 0.42 D) 0.52 E) 0.68

Q: What is the mole fraction of water in a water"ethanol solution that is 46.0% water by mass? (Ethanol is C2H5OH.) A) 0.28 B) 0.31 C) 0.25 D) 0.69 E) 0.54

Q: What is the mole fraction of water in a solution that contains 6.8 mol of ethanol (C2H5OH) and 1.2 mol of water? A) 0.15 B) 0.07 C) 0.57 D) 0.18 E) 0.85

Q: What is the mole fraction of toluene in a solution of 3.4 mol of benzene and 5.2 mol of toluene? A) 0.64 B) 0.54 C) 0.60 D) 0.24 E) 0.40

Q: What is the mole fraction of urea, CO(NH2)2,in a solution prepared by dissolving 6.8 g of urea in 33.5 g of methanol, CH3OH? A) 0.83 B) 0.17 C) 0.098 D) 0.90 E) 0.28

Q: What is the mole fraction of urea, CH4N2O, in an aqueous solution that is 36% urea by mass? A) 0.14 B) 0.86 C) 0.36 D) 0.55 E) 0.65

Q: Which of the following statements concerning the determination of crystal structure by x-ray diffraction is incorrect? A) X-rays are reflected from the repeating planes of an ordered crystal lattice. B) A diffraction pattern reveals the locations of the electrons in a crystal. C) Analysis of a diffraction pattern reveals the structure of a crystal. D) X-rays undergo constructive and destructive interference upon reflection in a crystal lattice. E) A diffraction pattern from a crystal depends on the incident angle of the x-rays.

Q: Lithium chloride crystallizes in a face-centered cubic structure. The unit cell length is 5.14x10-8cm. The chloride ions are touching each other along the face diagonal of the unit cell. The lithium ions fit into the holes between the chloride ions. What is the radius of the chloride ion?A) 2.52 x10-8cmB) 1.82 x10-8cmC) 2.56 x10-8cmD) 1.45 x10-8cmE) 2.82 x10-8cm

Q: The metal barium crystallizes in a body-centered cubic lattice. If the density of barium is 3.51 g/cm3, what is the atomic radius of barium? A) 15.1 pm B) 174 pm C) 42.5 pm D) 19.0 pm E) 219 pm

Q: The metal cesium crystallizes in a body-centered cubic lattice. If the density of cesium is 1.88g/cm3, what is the atomic volume of cesium?A) 1.60 x104pm3B) 7.99 x103pm3C) 3.99 x107pm3D) 6.01 x105pm3E) 7.98 x107pm3

Q: A metal crystallizes in a face-centered cubic lattice. The radius of the atom is 214 pm and the density of the element is 2.63 g/cm3. What is the molar volume of the metal? A) 98.9 cm3/mol B) 24.7 cm3/mol C) 86.6 cm3/mol D) 33.4 cm3/mol E) 0.380 cm3/mol

Q: A metal crystallizes in a face-centered cubic lattice. The radius of the atom is 125 pm and the density of the element is 8.91 g/cm3. What is the volume of the unit cell?A) 8.18 x106pm3B) 1.12 x109pm3C) 4.42 x107pm3D) 1.95 x106pm3E) 3.27 x107pm3

Q: What is the simplest formula of the compound represented by the unit cell provided below? A) AB3 B) AB2 C) AB D) A2B4 E) A2B6

Q: Copper crystallizes with a face-centered cubic unit cell. If the edge length of the unit cell is 362 pm, what is the radius of a copper atom in picometers? A) 128 pm B) 512 pm C) 1020 pm D) 296 pm E) 45.3 pm

Q: Sodium crystallizes in the body-centered cubic system. If the edge of the unit cell is 430 pm, what is the radius of a sodium atom in picometers? A) 186 pm B) 744 pm C) 992 pm D) 859 pm E) 80.5 pm

Q: The metal cesium crystallizes in a body-centered cubic lattice. If the density of cesium is 1.88g/cm3, what is the unit cell volume?A) 1.77 x106pm3B) 2.35 x104pm3C) 2.35 x108pm3D) 1.17 x108pm3E) 4.70 x104pm3

Q: The metal barium crystallizes in a body-centered cubic lattice. If the radius of barium is 222pm, what is the unit cell edge length? A) 513 pm B) 444 pm C) 296 pm D) 222 pm E) 96.1 pm

Q: The metal iron crystallizes in a body-centered cubic lattice. If the density of iron is 7.87g/cm3, what is the unit cell edge length? A) 287 pm B) 77.6 pm C) 75.0 pm D) 61.6 pm E) 228 pm

Q: Lithium chloride crystallizes in a face-centered cubic structure. The unit cell length is 5.14x10-8cm. The chloride ions are touching each other along the face diagonal of the unit cell. The lithium ions fit into the holes between the chloride ions. What is the density of the lithium chloride?A) 0.520 g/cm3B) 2.82 g/cm3C) 2.08 g/cm3D) 3.11 g/cm3E) 3.78 g/cm3

Q: Lithium chloride crystallizes in a face-centered cubic structure. The unit cell length is 5.14x10-8cm. The chloride ions are touching each other along the face diagonal of the unit cell. The lithium ions fit into the holes between the chloride ions. What is the mass of LiCl in a unit cell?A) 5.63 x10-22gB) 1.41 x10-22gC) 4.22 x10-22gD) 7.04 x10-23gE) 2.82 x10-22g

Q: Ytterbium crystallizes in a face-centered cubic lattice. The radius of ytterbium is 198 pm. What is the edge length of the unit cell? A) 560 pm B) 396 pm C) 792 pm D) 420 pm E) 198 pm

Q: Calcium crystallizes in a face-centered cubic lattice. The density of the element is 1.55 g/cm3. What is the volume of a single unit cell? A) cm3 B) cm3 C) cm3 D) cm3 E) cm3

Q: A metal crystallizes in a face-centered cubic lattice. The radius of the atom is 198 pm and the density of the element is 6.57 g/cm3. What is the identity of the metal? A) Cu B) Ca C) Sr D) Ni E) Yb

Q: The metal gold, with an atomic radius of 144.2 pm, crystallizes in a face-centered cubic lattice. What is the density of gold? A) 9.65 g/cm3 B) 1.21 g/cm3 C) 4.82 g/cm3 D) 2.41 g/cm3 E) 19.3 g/cm3

Q: The metal palladium crystallizes in a face-centered cubic lattice with an edge length of 388.8 pm. What is the density of palladium? A) 0.752 g/cm3 B) 3.01 g/cm3 C) 1.50 g/cm3 D) 6.01 g/cm3 E) 12.0 g/cm3

Q: Assuming the following metals all have the same unit cell structure, which of the following would be expected to have the highest density: Sc, Ti, Mn, or Co? A) Mn B) Ti C) Co D) Sc E) cannot be determined from the information given.

Q: Lithium chloride crystallizes in a face-centered cubic structure. The unit cell length is 5.14x10-8cm. The chloride ions are touching each other along the face diagonal of the unit cell. The lithium ions fit into the holes between the chloride ions. How many chloride ions are there in this unit cell?A) 4B) 3C) 1D) 8E) 2

Q: Which one of the following statements about solid Cu (face-centered cubic unit cell) is incorrect? A) It will conduct electricity. B) The length of a face diagonal is four times the Cu radius. C) The number of atoms surrounding each Cu atom is 12. D) The solid has a cubic closest-packed structure. E) There are two atoms per unit cell.

Q: A metal crystallizes in a face-centered cubic lattice. The radius of the atom is 196 pm and the density of the element is 1.55 g/cm3. How many atoms are there per unit cell? A) 4 B) 6 C) 8 D) 1 E) 2

Q: How many atoms are there in a body-centered cubic unit cell of vanadium? A) 4 B) 8 C) 6 D) 2 E) 1

Q: How many atoms are there in a cubic close-packed unit cell of aluminum? A) 4 B) 6 C) 1 D) 8 E) 2

Q: The unit cell in a certain lattice consists of a cube formed by an anion at each corner, an anion in the center, and a cation at the center of each face. The unit cell contains a net: A) 2 anions and 3 cations. B) 2 anions and 2 cations. C) 5 anions and 3 cations. D) 3 anions and 4 cations. E) 5 anions and 6 cations.

Q: The space-filling representation of a crystalline polonium provided below is an example of a _____ unit cell, which contains the equivalent of _____ atom(s) within a single unit cell. A) simple cubic, 1 atom B) body centered cubic, 2 atoms C) face centered cubic, 4 atoms D) simple cubic, 8 atoms E) body centered cubic, 3 atoms

Q: In any cubic lattice an atom lying at the corner of a unit cell is shared equally by how many unit cells? A) 1 B) 16 C) 2 D) 4 E) 8

Q: For a given pure metal which of the following cubic unit cells would result in the highest metal density? A) It depends on the identity of the metal. B) The density would be identical for all these cells if the edge length of each cell were the same. C) A face-centered cubic cell. D) A simple cubic cell. E) A body-centered cubic cell.

Q: Which of the following concerning the 2-D lattice provided below is/are correct?1) One possible unit cell contains a single A and a single .2) More than one unit cell which reproduces this lattice is possible.3) One possible unit cell contains four A's and four 's.A) 1 onlyB) 2 onlyC) 3 onlyD) 1 and 2E) 1, 2, and 3

Q: A solid crystal of NaCl is A) soft, low melting, a poor electrical conductor. B) soft, low melting, a good electrical conductor. C) hard, high melting, a good electrical conductor. D) hard, high melting, a poor electrical conductor. E) soft, high melting, a poor electrical conductor.

Q: A certain solid substance that is very hard, has a high melting point, and is nonconducting unless melted is most likely to be: A) CO2 B) I2 C) H2O D) NaCl E) Cu

Q: Which of the following pure substances has the highest normal boiling point? A) H2O B) CF4 C) CsF D) CaF2 E) KF

Q: Which of the following pure substances has the highest normal melting point? A) P4O10 B) P4O6 C) CO2 D) CaO E) Na2O

Q: Which of the following pure substances has the highest normal melting point? A) NO2 B) SiO2 C) CO2 D) P4O10 E) N2O5

Q: Which of the following pure substances is a solid at room temperature and pressure? A) NH3 B) PH3 C) SiH4 D) CH4 E) AlH3

Q: A low melting solid readily dissolves in water to give a nonconducting solution. The solid is most likely a A) molecular solid. B) ionic solid. C) covalent network solid. D) weak base. E) metallic solid.

Q: Which of the following pure substances has the highest melting point? A) KBr B) NaCl C) NaF D) CsI E) LiF