Chem 1411 Practice Exam 2

Chem 1411 Practice Exam 2

Instructions 1. Write your name on your exam. 2. You may use only the scratch paper and periodic table provided with the exam. You may also use a calculator, provided it cannot communicate with other devices. 3. When completed, turn in the exam, answer sheet, and all scratch paper, periodic tables, etc. This is a 50 minute exam with 20 questions. Good luck! Constants Avogadro s Constant 6.022 141 29 10 23 mol 1 Gas Constant 0.082 057 46 L atm/k mol = 8.314 J/K mol = 8314 g m 2 /K mol s 2 1 atm = 1.013 25 10 5 Pa = 760 mmhg = 760 Torr = 14.7 psi = 1.013 45 bar 1 cal = 4.184 J Formulas P V = nrt ( ( n ) ) 2 P + a (V nb) = nrt V M 1 V 1 M 2 V 2 P A = P tot χ A P total = P A + P B +... V rms = 3RT M rate 2 M1 = rate 1 M 2 Data Vapor Pressure of Water Temp ( C) P H2 O (mm Hg) 20 17.3 21 18.8 22 19.5 23 21.0 24 22.5 25 24.0 100 760.0

Solubility Rules Ion Solubility Exceptions Alkali Metals, Nitrates Soluble None Ammonium Soluble None Acetates, Chlorates, Perchlorates Soluble None Chlorides, Bromides, Iodides Soluble Ag +, Hg2 2+ are insoluble. PbCl 2, PbBr 2, PbI 2, and HgBr 2 are slightly soluble. Sulfates Soluble Sr 2+, Ba 2+, Pb 2+, Hg2 2+ are insoluble. CaSO 4 and Ag 2 SO 4 are slightly soluble. Hydroxides Insoluble Alkali metals, Ba 2+ are soluble. Sr(OH) 2 and Ca(OH) 2 are slightly soluble. Sulfides, Carbonates, Phosphates Insoluble Alkali metals, NH +, CaS, SrS, BaS are soluble.

Chem 1411-03 Practice Exam 2 1 Ch. 4 Aqueous Reactions 1. 10.00 g of CuCl 2 (s) is dissolved in 1.500 L of water. What is the concentration of Cl (aq)? A. 0.074 14 M B. 0.099 17 M C. 0.049 58 M D. 0.024 79 M E. 0.033 67 M 2. What is the molarity of Ca(NO 3 ) 2 (aq) when 40 ml of 2.0 M Ca(NO 3 ) 2 (aq) is diluted to a volume of 60 ml? A. 0.000 21 M B. 0.076 M C. 0.78 M D. 0.96 M E. 1.3 M 3. If Na 2 SO 4 (aq), Ba(OH) 2 (aq), and Ca(NO 3 ) 2 (aq) are added to water, the precipitates will be A. Ba 2 SO 4 (s),baoh (s), CaOH (s), CaSO 4 (s) B. Ba 2 SO 4 (s), Ca(OH) 2 (s), CaSO 4 (s) C. Ba 2 SO 4 (s), Ca(OH) 2 (s) D. Ba(OH) 2 (s), Ca 2 SO 4 (s) E. Na 2 SO 4 (s), Ba(OH) 2 (s), Ca(NO 3 ) 2 (s) 4. An Arrhenius base A. Forms insoluble compounds when reacted with an Arrhenius acid. B. Is a source of electrons. C. Generates OH in aqueous solution. D. Is covalently bonded to hydroxide. E. Reacts endothermically with water. 5. Which is the correct reaction of H 2 SO 4 (aq) and NaOH (aq)? A. H 2 SO 4 (aq) + NaOH (aq) H 3 NaSO 5 (s) B. H 2 SO 4 (aq) + 2 NaOH (aq) Na 2 SO 4 (aq) + 2 H 2 O (l)

Chem 1411-03 Practice Exam 2 2 C. H 2 SO 4 (aq) + NaOH (aq) NaSO 4 (aq) + H 2 O (l) D. H 2 SO 4 (aq) + NaOH (aq) NaH 2 (s) + HSO 4 (aq) E. H 2 SO 4 (aq) + NaOH (aq) NaSO 4 (aq) + H 2 (g) + O 2 (g) 6. If CaCl 2 (s) and Na 2 CO 3 (s) are added to a solution, the result would be A. CaCl 2 (s) and Na 2 CO 3 (s) B. CaCO 3 (s) and NaCl (s) C. Na + (aq), CO 2 3 (aq), and CaCl 2 (s) D. Na + (aq), Cl (aq), and CaCO 3 (s) E. Ca 2+ (aq), Cl (aq) and Na 2 CO 3 (s) 7. Which of the following is a weak acid? A. HClO 4 B. HCl C. H 2 SO 4 D. HCOOH E. HBr 8. A 10.0 ml sample of H 2 SO 4 (aq) of unknown concentration is titrated with 0.200 M NaOH in presence of an indicator. The indicator changes color when 10.0 ml of NaOH (aq) have been added. What was the concentration of the H 2 SO 4 (aq) sample? A. 0.250 M B. 0.500 M C. 0.100 M D. 0.200 M E. 0.400 M Ch. 5 Gases 9. What is an ideal gas? A. A gas in molecules have no volume or chemical interactions and undergo elastic collisions. B. A fluid which takes the shape of its container. C. A gas in which the type of gas determines how pressure, volume, moles, and temperature are related.

Chem 1411-03 Practice Exam 2 3 D. A gas which condenses into a liquid as the gas cools. E. A gas for which the properties must be determined by experiment. 10. What would be a valid equation relating a change in the number of moles of gas to its change in volume? A. V 1 n 1 = V 2 n 2 B. V 1 n 2 = V 2 n 1 C. P 1 V 1 n 1 = P 2 V 2 n 2 D. n = P V/RT E. P 1 + P 2 = (n 1 + n 2 )RT/V 11. The equivalence point is where A. All of the acid dissolves. B. Just enough acid or base has been added to neutralize the solution. C. The indicator is least likely to change color. D. Any solids become soluble. E. The same volume of acid and base have been added to the solution. 12. A light bulb contains argon gas and has a temperature of 260 C when turned on. What is the average velocity of an argon gas atom in the light bulb? A. 18.2 m/s B. 314 m/s C. 403 m/s D. 576 m/s E. 871 m/s 13. Which is not a property of an ideal gas? A. Gas molecules are chemically attracted to each other. B. Gas pressure is proportional to the number of molecules. C. It expands to fill the volume of its container. D. Gas molecules collide elastically. E. Its volume decreases with temperature. 14. A four quart saucepan holds 210 moles of H 2 O. If the water evaporates into a gas, what volume will it occupy? The outside pressure is 732 mm Hg, and the temperature is 300 K. A. 7.06 L B. 168 L

Chem 1411-03 Practice Exam 2 4 C. 1557 L D. 4600 L E. 5370 L 15. A syringe has a plunger which can freely move. It initially contains 5.0 ml of oxygen. It is cooled from 98 C to 15 C. What is the new volume of the oxygen? A. 0.8 ml B. 3.9 ml C. 4.7 ml D. 6.4 ml E. 8.7 ml 16. A balloon is filled to 100.0 L at 739 mm Hg and 22.0 C and is allowed to ascend to an altitude where the pressure is 362 mm Hg and the temperature is 15.3 C. What is the final volume of the balloon? A. 25.7 L B. 71.9 L C. 127 L D. 179 L E. 246 L 17. It takes 1 hour for a tire filled with CO 2 (g) to deflate. How much more quickly does this happen if the tire is filled with H 2 (g)? A. 0.21 as quickly B. 4.67 as quickly C. 18.1 as quickly D. 45.1 as quickly E. 96.2 as quickly 18. In which of the following cases would the ideal gas approximation be least valid? A. Calculating the number of moles of gas in an open room on earth s surface. B. A hot, low pressure gas. C. A single molecule in a large container. D. A gas for which molecular interactions were very small and the temperature was not too large. E. A very cold, high pressure gas, made of large molecules.

Chem 1411-03 Practice Exam 2 5 19. A reaction produces H 2 (g), which is collected over water in an inverted beaker. 740 ml of volume are displaced. The temperature is 24.0 C and the pressure in the room is 768 mm Hg. How many moles of H 2 were produced by the reaction? A. 0.0298 mol B. 0.0306 mol C. 0.369 mol D. 0.379 mol E. 0.798 mol 20. In the van der Waals equation ( ( n ) ) 2 P + a (V nb) = nrt V the term nb represents A. The reduction in pressure due to intermolecular attractions. B. The kinetic energy of the gas molecules. C. The concentration of the gas. D. The volume occupied by the molecules of the gas. E. The increase in pressure due to intermolecular attractions. Please turn in your exam, answer sheet, periodic table, all other papers used, and clear your calculator.