molality: m = = 1.70 m

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 1 Chem 12: Chapters 10, 11, 12, 13, 14 Unit 3 Worksheet 1. What is miscible? Immiscible? Miscible: two or more substances blend together for form a solution (water and alcohol). Like polarities will blend to make a solution. Immiscible: two or more substances create layers when added together (oil and vinegar). Nonpolar and polar substances generally do not blend into solutions. 2. What is saturated? Unsaturated? Supersaturated? Saturated solution: holds the maximum solute, no more will dissolve Unsaturated solution: more solute can still be added Supersaturated solution: unstable solution has more than the maximum solute. Any disturbance will cause the excess solute to come out. 3. How does Temperature affect a) the solubility of a gas in an aqueous solution? b) Solubility of a solid in aqueous solution. Generally the solubility of gas solutes in water decrease at higher temperatures Generally the solubility of solid solutes in water increase at higher temperatures 4. How does Pressure affect the solubility of a gas in an aqueous solution? Solubility of gas in water increases as the pressure of that gas above the liquid increases. 5. a) Will I 2 or CH 2 Cl 2 be more soluble in water? Explain. b) Which (CO 2 gas in water or KCl solid) is expected to be more soluble at higher temperatures c) Will CO 2 gas be more soluble in water when the container is pressurized with air or carbon dioxide? a) CH 2 Cl 2, water and this are both polar. b) KCl c) Pressurized with CO 2 6. For a solution is made adding together 12.0 g of KNO 3 and 70.0 grams of water. The density of the resulting solution is 1.08 g/ml. Solve for the mass %, Molarity, and molality. Mass percent: mass % = x 100% = 14.6% Molarity: M = = 1.57 M molality: m = = 1.70 m

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 2 7. Describe both quantitatively and qualitatively how you can prepare 300 ml of 2.00 M HCl solution from concentrated 12.0 M HCl solution. M 1 V 1 = M 2 V 2 require 50.0 ml of 12 M HCl and water In a container add about 200 ml of water, then 50.0 ml of 12 M HCl, mix and add more water until the total volume comes to 300 ml total 8. Solve for the grams of potassium nitrate in 40.5 grams of 14.8 % KNO 3 solution. 5.99 g KNO 3 9. Calculate the molarity of a solution prepared by dissolving 5.72 grams of NaOH in 43.8 ml of solution. 3.26 M NaOH 10. How many moles of NH4NO3 must be dissolved in 250 ml of solution to prepare a 0.452 M NH4NO3 solution? 0.113 mol NH 4 NO 3 11. If you evaporate to dryness all the water from a 450 g solution of 8.00% NaCl, how many grams of NaCl will remain? 39.0 g NaCl 12. A solution is produced by dissolving 6.75 grams of Ca(NO3)2 in water to produce 375 ml of solution that has a density of 1.03 g/ml. Calculate the mass percent of the Ca(NO3)2 in the solution. 1.75% Ca(NO 3 ) 2 13. What is osmosis? Osmosis is the flow of a solvent from a less concentrated solution to a more concentrated solution in the attempt to equal the two concentrations. Osmotic pressure is the pressure required to stop an osmotic flow. 14. What is the boiling point of an aqueous solution that is 5.00 m? The normal boiling point of water is 100 C, K b for water = 0.512 C. kg/mol. 102.56 C

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 3 15. Complete the following table for the indicated substances. substance SiF 4 CO3-2 OF2 K 2 SO 3 Draw the best 3 resonances Lewis structure(s), resonances, and 2 [K] +1-2 and SO 3 as trigonal structural pyramidal isomers if any with octet name electronic geometry around central atom tetrahedral Trigonal planar tetrahedral Tetrahedral for -2 SO 3 name molecular tetrahedral Trigonal planar bent Trigonal geometry around central atom a)show 3-D sketch with atoms & bonds in it b) Indicate polar bonds with dipole arrows toward the more electronegative pyramidal for SO 3-2 Bond angles 109.5 120 <109.5 <109.5 is it an ionic compound, polar molecule, nonpolar molecule or an ion? nonpolar ion Polar

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 4 16. What is stronger (single, double, triple) bond? What is longer? single 17. Using the Valence Shell Electron Repulsion (VSEPR) theory, fill in the angles for the number of Electron Regions (2) 180 (3) 120 (4) 109.5 18. Fill in the following tables: VSEPR drawings #of electron regions number of bonded atoms electronic geometry name molecular geometry name bond angles rough 3-D sketch an example molecule or ion 2 2 linear linear 180 O=C=O CO 2 4 2 tetrahedral bent 109.5 H 2 O 3 3 Trigonal planar trigonal planar 120 SO 3 19. What is the volume of 32.7 grams of F2 gas at STP? 19.3 L 20. What is the number of moles of gas in a 550 ml container at 30.0 C and 751 torr pressure? 0.0218 mol 21. 534 ml of CH4 gas was collected at 23 C and 754 torr. What new volume would the CH4 gas occupy at 732 torr and 46 C? 593 ml 22. 127 ml of N2 gas was collected by displacement of water at 25 C and 742 torr. What is the number of moles of N2 gas? (The vapor pressure of water at 25 C is 24 torr.) 4.90 x 10-3 mol 23. What pressure will 4.15 g of CO2 gas have when placed in a 320 ml container at 45.0 C? 7.69 atm 24. Nitrogen gas is placed into a steel tank until its pressure is 21.4 atm at 20 C. The maximum pressure the tank can safely contain is 50.0 atm. What is the highest temperature in C that this tank be safely heated? 411 C 25. a) Balance the following unbalanced equation: C5H12 (g) + 8O2 (g) 5CO2 (g) + 6H2O (g) b) What volume of CO2 gas at STP will be produced from 144 g of C5H12? 156 L 26. Balance 3 H2 (g) + N2 (g) 2NH3 (g) all gases at same temperature and pressure. How many cubic centimeters of H2 gas are required to produce 200 cm3 of ammonia gas? 300 cm 3 H 2

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 5 27. A vessel with an internal volume of 10.0 L contains 7.00 g of nitrogen gas (N 2 ), 1.00 g of Helium gas (He), and 3.20 g of oxygen gas (O 2 ). At 25 C, what is the partial pressure from each substance and what is the total pressure inside the vessel? 0.250 mol N 2, 0.250 mol He, and 0.100 mol O 2 ; total moles = 0.600 mol 0.611 atm N 2, 0.611 atm He, and 0.245 atm O 2 ; total pressure = 1.47 atm 28. A 450 ml sample of nitrogen gas at 21 C and 0.987 atm is heated and expands to 9.00 L at a new pressure of 75.0 torr. What is the final temperature in C 588 K = 315 C 29. What are characteristics of an ideal gas according to the kinetic molecular theory? Assumptions for the KMT 1. An ideal gas consists of tiny particles in constant, random, straight-line motion. 2. Particles exhibit no attraction or repulsion between each other. Collisions of gas particles are elastic. 3. There is a lot of space between particles. The volume of the particles themselves is negligible compared to the total volume of the gas. 4. The speed of particles increases with increasing temperature. The average kinetic energy of gas particles is proportional to the Temperature in Kelvin. 30. It is recommended to check the air pressure in your car tires when they are cold, not after driving a great distance when they are warm. Explain what kind of pressure reading difference one can expect. After driving the temperature of the tires increase and that will increase the tire pressure. 31. A gas is collected over water at a certain temperature. The total pressure is 747 torr. The vapor pressure of water at this temperature is 22 torr. What is the partial pressure of the dry gas collected? 725 torr 32. Balance the following unbalanced equation: C 6 H 12 O 6 (s) + 6 O 2 (g) 6 CO 2 (g) + 6 H 2 O (g) From the 75.0 g of O2 and 35.0 g of C6H12O6, determine how much carbon dioxide can theoretically be produced in units of moles, liters at STP, and grams of CO 2? Which is the limiting reactant? 75.0 g O 2 can produce 2.34 moles of CO 2 35.0 g C 6 H 12 O 6 can produce 1.17 moles of CO 2 Limiting reactant is the sugar, C 6 H 12 O 6 1.17 moles CO 2, 26.1 L O 2 at STP, 51.3 g CO 2

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 6 33. Fill in the term for each definition or description: Hydrogen bonding A special kind of strong dipole-dipole attraction which occurs among molecules when a H atom is bonded to a highly electronegative atom such as N, O, or F. Intermolecular force Forces between molecules Molarity A unit of concentration that measures mole solute per liter solution Normal boiling pt The temperature point at which the vapor pressure of a liquid is equal to the normal atmospheric pressure of 760 torr or 1 atm. ph A scale used to quantitatively measure the acidity or basicity of an aqueous solution. 34. What type of intermolecular bonds will the following have? (draw Lewis structures to help visuallize) (a)-dipole-dipole attraction, (b)-hydrogen bonding, (c)-london dispersion forces B H2O B HF C CH4 C Br2 B NH3 A HI 35. The vapor pressure at 20 C is given for the following substances: H2O 17.5 torr and Br2 173 torr a) Which liquid is more volatile? Br2 173 torr b) What type of intermolecular forces does each of these have? H2O hydrogen bonding and Br2 London Dispersion Forces c) Explain why the difference in vapor pressure at 20 C makes sense. Weaker attraction forces found in Br 2 will cause the substance to have a higher vapor pressure, more liquid molecules will have the required energy to escape the attractions and become gas. 36. a) Finish and balance the following acid / base reaction: HC 2 H 3 O 2 (aq) + NaOH (aq) NaC 2 H 3 O 2 (aq) + H 2 O (l) Acid (HC 2 H 3 O 2)-------------------- -conjugate base (C 2 H 3 O 2-1 ) Base (OH -1 )-----------------------conjugate acid (H 2 O) b) For the above balanced equation, label and draw lines connecting the acid and its conjugate base, and the base and its conjugate acid. c) A titration starts with 25 ml of 0.42 M HC2H3O2, acetic acid, solution. 42.5 ml of NaOH solution are then added to neutralize the solution. Calculate the moles of HC2H3O2 initially, the moles of NaOH used, and the molarity of the NaOH solution. 0.0105 moles of HC2H3O2, 0.0105 moles of NaOH used, 0.247 M NaOH

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 7 37. A KOH solution is standardized using KHP. Using the following titration data, calculate the molarity of the KOH solution. (the molecular weight of KHP is 204.2g/mol) KOH buret readings: final initial 32.65 ml 12.73 ml mass of flask + KHP mass of empty flask 144.301 g 143.422 g used 19.92 ml KOH mass of KHP 0.879 g 0.216 M KOH 38. Given the following ph values label each as acidic, basic or neutral. ph = 7 neutral ph = 3 acid ph = 9 base ph = 0.5 acid 39. Fill in the missing pieces of this table acid, base, or neutral? [H+] [OH-] ph poh Base 7.2 x 10-12 1.4 x 10-3 11.14 2.86 Neutral 1.0 x 10-7 1.0 x 10-7 7.0 7.0 Base 2.5 x 10-9 4.0 x 10-6 8.6 5.4 Base 3.2 x 10-11 3.2 x 10-4 10.5 3.5 Acid 2.0 x 10-4 5.0 x 10-11 3.7 10.3 K w = 1.0 x 10-14 = [H +1 ][OH -1 ] ph = -log[h +1 ] [H +1 ] = 10 -ph poh = -log[oh -1 ] [OH -1 ] = 10 -poh pk w = -log[k w ] pk w = ph + poh = 14 Acid has a ph < 7 Neutral has ph = 7 Base has a ph > 7

C h e m i s t r y 1 2 U n i t 3 R e v i e w P a g e 8 40. Circle the letters of the following which are not a conjugate acid-base pair. Circle the acid and underline the base for each conjugate acid-base pair. a) HCl, Cl- b) Cl-, ClO4 - c) H3PO4, PO4-3 d) H2SO4, HSO4 - e) NH3, NH4 + f) H2O, H3O+ 41. Answer the following as true or false. For the false statements what must be changed to make them true?: F A solution is a homogeneous mixture which can only be found in the liquid state. T A buffered solution resists change in its ph even when a strong acid or base is added. F A buffered solution always contains a strong acid and its conjugate base. F A weak acid will completely dissociate in water. F A combination of HCl and NaCl would make a good buffer solution T A combination of HCN and KCN would make a good buffer solution. T An amphoteric substance can act as either an acid or a base T An acid-base reaction is often called a neutralization reaction because the acid and base are neutralized by creating water. F If more solute is added to a solution that is saturated, that solute will dissolve and make the solution more concentrated. F When an ionic solution such as NaCl dissolves in water, the NaCl molecules stay attached to each other. F It is possible to have an aqueous solution with 0.0007 M [H+] and 0.0000003 M [OH-] F Cl- is the conjugate acid of HCl. T A pipet will deliver a specified amount of liquid with great accuracy. 42. 30.0 ml of 0.240 M NaOH is required to stoichiometrically react with 20.0 ml of HCl solution. Write the balanced acid-base equation and calculate and Molarity of the HCl solution? HCl (aq) + NaOH (aq) H 2 O (l) + NaCl (aq) 0.360 M HCl