Surface Tension; Capillary Action; Crystalline Solid; Amorphous Solid; Substitutional Alloy; Interstitial Alloy; Silica; Silicate; Glass; Ceramic

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Georgia Cox
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1 HOMEWORK 3A Surface Tension; Capillary Action; Crystalline Solid; Amorphous Solid; Substitutional Alloy; Interstitial Alloy; Silica; Silicate; Glass; Ceramic 1. For each of the following states of matter, tell (1) if the volume is definite or indefinite, (2) if the shape is definite or indefinite, and (3) the type of motion the individual particles undergo: (a) solid (b) liquid (c) gas 2. Describe the relationship between the kinetic energy of the particles and the attractive forces between the particles in each of the following states of matter: (a) solid (b) liquid (c) gas 3. Tell how the following physical properties depend on the strength of intermolecular forces: (a) surface tension (b) viscosity 4. Distinguish between a crystalline solid and an amorphous solid. 5. Identify the interparticle attractive forces found in an ionic substance. 6. Identify the interparticle attractive forces found a metallic substance. 7. Identify the interparticle attractive forces found a macromolecular substance. 8. Identify the particles that make up each of the following types of matter, and identify the interparticle attractive forces found in each: (a) Mo (d) MgCl 2 (c) Si 9. Draw atomic level pictures of the three substances in question Given unlabeled samples of the three substances in question 8, how could they be identified experimentally?

2 HOMEWORK 3B Intramolecular Bonding; Intermolecular Forces; Dipole-Dipole Attraction; Hydrogen Bonding; London Dispersion Forces 1. Identify the intermolecular attractive forces found in each of the following: (a) a nonpolar molecular substance (b) a polar molecular substance 2. Identify the particles that make up each of the following types of matter, and identify the interparticle attractive forces found in each: (a) Fe (b) Na 2 O (c) SiO 2 (d) CO (e) HF (f) P 4 (g) Xe (h) CHCl 3 3. Draw atomic level pictures of the eight substances in question Given unlabeled samples of solid C 6 H 12 O 6 and NaCl, how could they be identified experimentally? HOMEWORK 3C Band Model; Semiconductor; n-type Semiconductor; p-type Semiconductor; Rectifier 1. For a copper wire (a) draw a band diagram for the copper showing no potential being applied to the wire (b) draw a band diagram for the copper showing a potential being applied to the wire (c) explain why the copper wire conducts electricity 2. Draw a band diagram for each of the following. (a) lead (c) germanium (e) germanium doped with arsenic (b) diamond (d) germanium doped with lithium

3 HOMEWORK 3D 1. Predict the ionic substance in each pair that has the greater melting point, and explain why: (a) AgCl or ZnS (b) CrBr 2 or WBr 2 2. Predict the metallic substance in each pair that has the greater melting point, and explain why: (a) Cd or Hg (b) Sr or Zr (c) Os or Pt 3. Predict the macromolecular substance in each pair that has the greater melting point, and explain why: (a) C or Si (b) B or C 4. Draw Lewis structures and bond-orbital- models for each of the following molecular substances, and predict whether they are polar or nonpolar. (a) CH 3 CH 3 (b) CH 3 CH 2 CH 3 (c) H 2 CO (d) CH 3 OH 5. Predict the molecular substance in each pair that has the greater melting point, and explain why: (a) CH 3 CH 3 or CH 3 CH 2 CH 3 (b) CH 3 CH 3 or H 2 CO (c) CH 3 OH or H 2 CO 6. Explain the boiling points of the following three substances: O O O CH 3 C-OH ClCH 2 C-OH CH 3 C-OCH C 189 C 57 C 7. For each set of substances, rank them from lowest to highest melting points, and explain why based upon the type of particles and interparticle attractive forces found in each. (a) Xe, Fe, Ni (b) NaCl, MgCl 2, CCl 4, (c) HF, HCl, HBr (d) P 4, S 8, SiO 2

4 HOMEWORK 3E Vaporization; Heat of Vaporization; Condensation; Equilibrium; Vapor Pressure; Heat of Fusion; Normal Melting Point; Normal Boiling Point; Supercooled; Superheated 1. Explain how each of the following affect the rate of evaporation of a liquid in an open dish: (a) temperature (b) surface area (c) intermolecular forces 2. A 25.0 g snowball at C is thrown at a wall so hard that the snowball completely vaporizes, producing steam at C. Calculate the amount of energy the snowball absorbed upon impact with the wall. The specific heat capacity for ice is 2.22 J/gC, the specific heat capacity for water is 4.18 J/gC, and the specific heat capacity for steam is 2.01 J/gC. The heat of fusion for ice is 335 J/g and the heat of vaporization for water is 2260 J/g.

5 HOMEWORK 3F Triple Point; Critical Pressure; Critical Temperature 1. Use the phase diagram below to answer the following questions: (a) Identify the phases present at points A, B and C (b) Identify the normal melting point and the normal boiling point of the substance (c) Identify the triple point temperature and pressure (d) Identify the critical temperature and critical pressure (e) Describe what happens to the substance as it is warmed from -100 C to 0 C at a pressure of 0.2 atm (f) Identify the more dense phase: solid or liquid 2. The normal freezing and boiling points of ammonia are -78ºC and -33ºC, respectively. The triple point is at -79ºC and 50 torr. (a) Use the data above to draw a phase diagram for ammonia, labeling (1) the axis s, (2) the regions in which the solid, liquid and gas phases are stable, and (3) the normal freezing point, (4) the normal boiling point, and (5) the triple point. (b) Describe any changes that can be observed in a sample of liquid ammonia when the temperature is increased from -50ºC to 0ºC at a constant pressure of 500 torr. (c) Describe any changes that can be observed in a sample of gaseous ammonia when the pressure is increased from 100 torr to 1000 torr at a constant temperature of -50ºC. (d) Identify the denser phase: solid or liquid

6 HOMEWORK 3G Hydration; Strong Electrolytes; Weak Electrolytes; Nonelectrolytes 1. Indicate which solvent, hexane (C 6 H 14 ) or water, would be more suitable for dissolving each of the following: (a) NaCl (b) HF (c) C 8 H 18 (d) Br 2 2. For each of the following pairs, indicate which substance would be more soluble in water: (a) NH 3 or PH 3 (b) CH 3 CN or CH 3 CH 3 O O (c) CH 3 C-OH or CH 3 C-OCH 3 (d) CH 3 CH 2 OH or CH 3 (CH 2 ) 14 CH 2 OH 3. A typical detergent is sodium dodecylsulfate, CH 3 (CH 2 ) 10 CH 2 SO 4 - Na +. Explain how this detergent helps to remove oil and dirt from clothes in a washing machine. 4. State the type of substances that are (1) strong electrolytes, (2) weak electrolytes, and (3) nonelectrolytes 5. State whether each of the following is a strong electrolyte, weak electrolyte, or nonelectrolyte, and complete each equation, showing how the solute would be expressed accurately in solution: (a) KCl (s) (b) Mg(C 2 H 3 O 2 ) 2 (s) (c) C 12 H 22 O 11 (s) (d) HNO 3 (g) 6. Complete the following table: (e) H 2 SO 3 (g) Soluble in H 2 O (Yes or No) Ionizes or Dissociates in H 2 O (No, a little, a lot) CCl 4 C 6 H 12 O 6 CH 3 OH NaBr HCl H 2 CO 3

7 HOMEWORK 3H Molarity; Mass Percent; Mole Fraction; Thermal Pollution 1. Calculate the mass percent of solute in each of the following solutions. (a) 21.6 g of sodium nitrate dissolved in g of water. (b) 55.1 g of sucrose (C 12 H 22 O 11 ) dissolved dissolved in 478 g of methanol. 2. Calculate the mole fraction of solute in each of the following solutions. (a) 4.50 moles of dextrose (C 12 H 22 O 11 ) dissolved in moles of water. (b) 12.5 grams of naphthalene (C 10 H 8 ) dissolved in 75.0 grams of cyclohexane (C 6 H 12 ). 3. Calculate the molarity of solute in each of the following solutions. (a) 1.58 moles of glucose dissolved in enough water to make 5.0 liters of solution. (b) 15.5 g of sodium chloride dissolved in enough water to make 1.50 liters of solution. 4. Calculate the molality of solute in each of the following solutions. (a) 2.14 moles of fructose dissolved in kilograms of water. (b) 27 g of ethanol (C 2 H 5 OH) dissolved in 345 ml of cyclohexane. The density of cyclohexane is g/ml. 5. Calculate the molarity of each ion present in each of the following solutions. (a) 0.25 M iron (III) bromide (b) 0.44 M magnesium nitrate 6. Calculate the number of grams of sodium hydroxide needed to prepare ml of a M sodium hydroxide solution. 7. A solution is prepared by dissolving 25.0 g of potassium fluoride in 80.0 g of water. The volume of the solution is ml. Fill out the unshaded regions in the table below, then calculate the following concentration units Mass (g) Quantity of Matter (mol) Volume (ml) Solute Solvent Solution (total) (a) mass percent of potassium fluoride (c) molality of potassium fluoride (b) molarity of potassium fluoride (d) mole fraction of potassium fluoride

8 HOMEWORK 3I Ideal Solution 1. Calculate the vapor pressure of each of the following solutions at 21 C if the vapor pressure of pure water is 18.7 torr at 21 C. (a) 0.25 moles of urea (CH 4 N 2 O), a nonelectrolyte, dissolved in 9.75 moles of water. (b) 0.25 moles of magnesium chloride dissolved in 9.75 moles of water. 2. Calculate the vapor pressure of each of the following solutions at 23 C if the vapor pressure of pure water is 21.1 torr at 23 C. (a) 17.6 grams of urea (CH 4 N 2 O), a nonelectrolyte, dissolved in 125 grams of water. (b) 17.6 grams of magnesium chloride dissolved in 125 grams of water. 3. Pentane (C 5 H 12 ) and hexane (C 6 H 14 ) form an ideal solution. At 25 C, the vapor pressures of pentane and hexane are 511 torr and 150. torr, respectively. A solution is made by mixing 25 ml of pentane (density = 0.63 g/ml) with 45 ml of hexane (density = 0.66 g/ml). (a) Calculate the mole fractions of pentane and hexane in the solution (b) Calculate the equilibrium vapor pressure of the solution 4. Consider the following five liquids and/or solutions at 25 C: pure water (vapor pressure of water = 23.8 torr) a 0.1 m solution of glucose in water a 0.1 m solution of sodium chloride in water a 0.1 m solution of calcium chloride in water a 0.1 m solution of methanol in water (vapor pressure of methanol = 143 torr) Place the liquids and/or solutions in order of lowest vapor pressure to highest vapor pressure. 5. Have access to Handout 5 from the Class Web Site.

9 HOMEWORK 3J Colligative Properties 1. Consider the following five liquids and/or solutions at 25 C: pure water (vapor pressure of water = 23.8 torr) a 1.0 m solution of sucrose in water a 1.0 m solution of potassium chloride in water a 1.0 m solution of hypochlorous acid in water a 1.0 m solution of magnesium chloride in water (a) Place the liquids and/or solutions in order of lowest boiling point to highest boiling point (b) Place the liquids and/or solutions in order of lowest freezing point to highest freezing point 2. A solution is prepared by dissolving moles of magnesium iodide in kilograms of water. Calculate (a) the freezing point of the solution (b) the boiling point of the solution. 3. A solution is prepared by dissolving 49 grams of sucrose (C 12 H 22 O 11 ) in 175 grams water. Calculate (a) the freezing point of the solution (b) the boiling point of the solution. 4. A solution containing 3.75 grams of a nonvolatile pure hydrocarbon in 95 grams of ethyl ether has a boiling point of 35.5 C. Determine the molar mass of the hydrocarbon. 5. Anthraquinone is 80.7% carbon, 3.9% hydrogen, and 15.4% oxygen by mass. When 1.32 grams of anthraquinone are dissolved in 11.4 grams of camphor, the freezing point of the solution is C. For anthraquinone, calculate its (a) empirical formual (b) molar mass (c) molecular formula. HOMEWORK 3K Semipermeable; Osmosis; Dialysis; Isotonic Solutions 1. The cells of a redwood tree have a concentration of sodium chloride of approximately 0.25 molar greater than ground water. At 20. C, calculate the osmotic pressure that would develop in the cells of the redwood tree through the cell membranes. 2. A gram sample of a protein is dissolved in water at 25 C to make 25.0 ml of solution. The osmotic pressure of the solution is 0.56 torr. Calculate the molar mass of the protein. 3. Historically, people would salt meat to preserve it. Explain why this is done.

HOMEWORK 3R 1. What are the two most efficient ways to pack spherical atoms, and what unit cells do they produce? 2. Perovskite is a mineral containing calcium, titanium, and oxygen.

10 HOMEWORK 3R 1. What are the two most efficient ways to pack spherical atoms, and what unit cells do they produce? 2. Perovskite is a mineral containing calcium, titanium, and oxygen. Two different representations of the unit cell are shown below. Show that both these representations give the same formula. 3. Cobalt has a cubic closest packing structure as a solid. Assuming that cobalt has an atomic radius of nm, calculate the density of solid cobalt. 4. Titanium metal exists in a body-centered-cubic structure. The density of titanium is 4.50 g/ml. Calculate the atomic radius of titanium. 5. Identify the most important types of interparticle forces present in each of the following substances: (a) BaSO 4 (b) H 2 S (c) C 2 H 6 (d) CsI (e) Cr (f) Si (g) Kr (h) CHCl 3 (i) BH 3 (j) NH 4 Cl (k) N 2 H 4 (l) Teflon, CF 3 (CF 2 ) n CF 3 6. Predict and explain which substance in each of the following pairs has the greatest melting point. (a) CH 3 CH 3 and CF 3 CF 3 (b) CH 3 CH 2 CH 2 CH 2 CH 3 and C(CH 3 ) 4 (c) PF 3 and PF 5 (e) CH 3 OCH 3 and CH 3 CH 2 OH (g) CuBr and CuBr 2 (i) Cs and W (d) HCl or HBr (f) LiCl and HCl (h) NiO and PdO (j) Cd and Hg 7. Given unlabeled samples of solid K 2 SO 4, Fe, B, C 5 H 10 O 5 and C 10 H 8, how could they be identified experimentally? 8. Use band theory to explain why each of the following increases the conductivity of a semiconductor: (a) increasing the temperature (c) adding an impurity (b) irradiating with light 9. Explain why the meniscus of water in a glass tube is different from the meniscus of mercury in a glass tube. (continued on next page)

11 10. Use the phase diagram below to answer the following questions: (a) Identify the phases that are present at points A through G (b) Identify the triple point and the critical point (c) Identify the normal melting point and the normal boiling point. 11. A substance has the following properties: H fus = 120 J/g MP = -15 C C(s) = 3.0 J/gC H vap = 480 J/g BP = 75 C C(l) = 2.0 J/gC C(g) = 1.0 J/gC Calculate the amount of heat needed to raise the temperature of 50.0 grams of the substance from 0. C to 100. C. 12. Indicate which solvent, carbon tetrachloride or water, would be more suitable for dissolving each of the following: (a) Cu(NO 3 ) 2 (b) CS 2 (c) C 6 H 6 (d) HF 13. For each of the following pairs, indicate which substance would be more soluble in water: (a) CH 3 OH or CH 3 CH 3 (b) CH 3 CH 2 OH or CH 3 OCH State whether each of the following is a strong electrolyte, weak electrolyte, or nonelectrolyte, and complete each equation, showing how the solute would be expressed accurately in solution: (a) K 2 CrO 4 (s) (c) H 2 SO 4 (g) (b) Al(ClO 3 ) 3 (s) (d) H 2 SO 3 (g) 15. A solution is prepared by dissolving 50.0 g of cesium chloride in 50.0 g of water. The volume of the solution is 63.3 ml. Calculate the (a) mass percent of cesium chloride (c) molality of cesium chloride (continued on next page) (b) molarity of cesium chloride (d) mole fraction of cesium chloride

12 16. A solution is prepared by dissolving 50.0 g glucose (C 6 H 12 O 6 ) in g water. If the vapor pressure of pure water is 23.8 torr at 25 C, calculate the vapor pressure of the glucose-water solution at 25 C. 17. At 40 C, a solution is prepared by mixing 10.0 grams of methanol (CH 3 OH) and 20.0 grams of propanol (CH 3 CH 2 CH 2 OH). At 40 C, the vapor pressures of methanol and propanol are 303 torr and 45 torr, respectively. (a) Calculate the mole fractions of methanol and propanol in the solution (b) Calculate the vapor pressures each of methanol and propanol in the solution, and the total vapor pressure of the solution 18. Consider the following four water solutions at 25 C: a 0.1 m solution of glucose a 0.1 m solution of nitrous acid a 0.1 m solution of hydrochloric acid a 0.1 m solution of sulfuric acid Place the liquids and/or solutions in order of lowest boiling point to highest boiling point 19. Calculate the freezing point and boiling point of a solution that is prepared by dissolving 2.0 grams of aluminum nitrate in 25.0 grams of water. 20. Reserpine is a natural product used as a tranquilizer and sedative. When 1.00 gram of reserpine is dissolved in 25.0 grams of camphor, the freezing point of the solution is C. Calculate the molar mass of reserpine. 21. Calculate the osmotic pressure at 25 C of a 0.50 M solution of calcium nitrate in water. HOMEWORK 3R ANSWERS 1. cubic closest packing face centered cubic units cells hexagonal closest packing - hexagonal prism unit cell 2. CaTiO g/ml cm 5. (a) ionic bonds (b) dipole-dipole attractions (c) London dispersion forces (d) ionic bonds (e) metallic bonds (f) covalent bonds (g) London dispersion forces (h) dipole-dipole attractions (i) London dispersion forces (j) ionic bonds (k) hydrogen bonds (l) London dispersion forces (continued on next page)

13 6. (a) CF 3 CF 3 Both are nonpolar molecular substances, with only London dispersion forces between the molecules. CF 3 CF 3 has more electrons, so it is more polarizing, making the LDF s stronger. (b) CH 3 (CH 2 ) 3 CH 3 Both are nonpolar molecular substances, with only London dispersion forces between the molecules. CH 3 (CH 2 ) 3 CH 3 molecules are longer and flatter, so there are more close atoms in neighboring molecules, making the LDF s stronger. (c) PF 3 PF 3 is a polar molecular substance, with London dispersion forces and dipole-dipole attractions between the molecules. PF 5 is a nonpolar molecular substance, having only LDF s between the molecules. (d) HBr Both are polar molecular substances, with London dispersion forces and dipole-dipole attractions between the molecules. HBr has more electrons, so it is more polarizing, making the LDF s stronger. (e) CH 3 CH 2 OH CH 3 CH 2 OH is a polar molecular substance, with London dispersion forces, dipoledipole attractions, and hydrogen bonding between the molecules. CH 3 OCH 3 is a polar molecular substance, but only has LDF s and DDA s between the molecules. (f) LiCl LiCl is an ionic substance, with strong ionic bonds between the ions. HCl is a polar molecular substance, with only the weak London dispersion forces and dipole-dipole attractions between the molecules. (g) CuBr 2 Both are ionic substances with ionic bonds between the ions. CuBr 2 has a higher charged copper ion, so it attracts more strongly to the bromide ions. (h) NiO Both are ionic substances with ionic bonds between the ions. Ni 2+ is a smaller cation than Pd 2+, so Ni 2+ can get closer to the oxide ion, attracting more strongly. (i) W Both are metallic substances with metallic bonds between the atoms. W has more net bonding electrons per atom than Cs (6 to 1), which attract to the bonding nuclei more strongly. (j) Cd Both are metallic substances with metallic bonds between the atoms. They both have the same number of net bonding electrons per atom, but Cd atoms are smaller, so the bonding electrons are in smaller molecular orbitals, which attract to the bonding nuclei more strongly. 7. The only conductor as a solid will be Fe. K 2 SO 4 and C 5 H 10 O 5 are the only water soluble substances; the water solution of K 2 SO 4 will conduct, the water solution of C 5 H 10 O 5 will not. Of the other two, B will have a high melting point, C 10 H 8 will not. 8. (a) With an applied electric potential, valence band orbitals are still lower in energy than conduction band orbitals because of the band gap. An increase in the temperature will provide the necessary energy for valence band e - s to be promoted to the higher energy conduction band. (b) With an applied electric potential, valence band orbitals are still lower in energy than conduction band orbitals because of the band gap. The energy from the photons of light will provide the necessary energy for valence band e - s to be promoted to the higher energy conduction band. (c) An impurity with more than four valence electrons per atom will create a band of electrons higher in energy than the band gap, called the donor band. When an electric potential is applied, the donor band electrons are higher in energy than the conduction band orbitals, so electrons will move from the donor band to the conduction band. An impurity with less than four valence electrons per atom will create an empty band lower in energy than the band gap, called the acceptor band. When an electric potential is applied, the valance band electrons are higher in energy than the acceptor band orbitals, so electrons will move from the valance band to the acceptor band. (continued on next page)

14 9. Polar water molecules are attracted to the polar glass, and this capillary action causes water to creep up the sides of the glass tube. 10. (a) A: solid B: liquid C: gas D: solid, gas E: solid, liquid, gas F: liquid, gas G: liquid, gas (b) triple point: E (c) normal melting point: -15 C ,000 J critical point: G normal boiling point: 75 C 12. (a) H 2 O (b) CCl 4 (c) CCl 4 (d) H 2 O 13. (a) CH 3 OH (b) CH 3 CH 2 OH 14. (a) K 2 CrO 4 (s) 2K + (aq) + CrO 2-4 (aq) (b) Al(ClO 3 ) 3 (s) Al 3+ - (aq) + 3ClO 3 (aq) (c) H 2 SO 4 (g) 2H + (aq) + SO 2-4 (aq) (d) H 2 SO 3 (g) H 2 SO 3 (aq) 15. (a) 50.0% (b) 4.69 M (c) 5.94 m (d) torr 17. (a) methanol, propanol (b) 147 torr methanol, 23 torr propanol, 170. torr total 18. lowest boiling point to highest boiling point: glucose, nitrous acid, hydrochloric acid, sulfuric acid 19. freezing point: -2.8 C; boiling point: C g/mol atm

1. Draw pictures on the atomic level for a solid, a liquid, and a gas.

EXTRA HOMEWORK 3A 1. Draw pictures on the atomic level for a solid, a liquid, and a gas. 2. What must be true about the kinetic energy of the particles making up a liquid if the liquid is to turn into