CHEM-100L [All] Midterm (Fall 03)

CHEM-100L [All] Midterm (Fall 03) - CHEM 136 Principles of...

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Unformatted text preview: CHEM 136 Principles of Chemistry Lab Midterm Exam Fall 2003 Name: Instructor (circle your section): Carl Aronson TU-8z00 TH-3:35 Cynthia Aronson TU-l:20 TU-3:35 Bell TU-8:00 TU-10215 W-10:15 Doyle TH-8z00 TH-3z35 Lewis TH-l :25 McAllister TU—1:20 TU:10:15 TH-10:15 TH-6z00 Seeley W-1:20 Wang TH-8:00 TH-l :20 MARK ALL ANSWERS ON BOTH THE EXAM AND THE SCANTRON. A PERIODIC TABLE IS GIVEN ON THE LAST PAGE. YOU MAY DETACH IT. 1. When working with chemicals, one should always return unused reagents to their original containers read instructions and chemical labels carefully add water to acid when preparing a dilute acid solution dispose of liquid chemicals down the drain Dow> 2. What is the volume of3.25g ofa solution with a density of 1.375 g/mL? A. 0.133 mL B. 4.47 mL C. 7.49 mL D. 2.36 mL E. 0.42 mL 3. For the graduated cylinder shown here, what is the volume ofliquid? 3 A. 6.32 mL B. 7.28 mL 3 .g C. 8.69 mL ’: " ’ D. 7.30 mL A E. 6.62 mL at“? a? a 4. Based on the following data, calculate the % ionization of acetic acid in the 2.50 x 10'3 M solution. [Acetic Acid] Measured conductivity (M) 2.50 x 10'5 7 2.50 x 10‘4 120 2.50 x 10‘3 248 2.50 x 10‘2 487 A. 27.6% B. 7.88% C. 35.4% D. 7.90% E. 2.82% 5. An aqueous solution with [H+] = 3.50x10'4 M A. has [OH'] = 2.86E-11 M B. is basic C. has a pH > 5 D. has a pOH of l 1.5 6. Which ofthe following has the lowest pH? A. 0.1 M HCl B. 0.1 M NaOH C. 0.1 M acetic acid D. 0.1 MNH3 E. None, all have the same pH. 7. A standardized NaOH solution has a concentration of 1.50 M. A 5.75 g sample of an unknown monoprotic acid in water required 40.0 mL ofthe NaOH solution to reach a phenolphthalein endpoint. The molecular weight ofthe unknown acid (g/mol) is A. 40.3 B. 60.4 C. 95.8 D. 190 8. Which ofthe following parameters is a measure of the accuracy ofa measurement? A. standard deviation B. mean C. relative error D. variance E. %RSD 9. The pH ofa solution is 6.0. What are the [H+] and [OH’] in this solution? K“: 1.0x 10‘” + A, [H ]=10'3M,[OH']:10'3 M B. [W] = 10‘8 M, [OH‘] = 10‘6 M C. [if] = 10‘2M, [OH‘] = 10‘4 M D. [Ht] = 10‘6M, [OH‘] = 10‘8 M E. None ofthe above. 10. lfa fire occurs in the chemistry lab, you should: A. Go into the tunnel and wait. B. Run up and down the hallway shouting, “FIRE!” C. Shut off equipment and exit the building. D. Ignore it and continue with the experiment. E. Go to the health service area so you can give first aid to smoke victims. 1 l. The conductivity ofa solution decreases as the number of in solution A. anions, increases B. electrons, decreases C. cations, increases D. ions, decreases E. electrons, increases 12. Which ofthe following is used “to deliver” (TD) 3 solution? A. Erlenmeyer flask B. volumetric pipet C. volumetric flask D. beaker 13. When an excess of K1 was added to 4.0 mL ofa Pb2+ solution, 0.36lg of Pblz (MW=461g/mol) was recovered. The concentration of Pb2+ in the original solution was: A. 0.26 M B. 0.039 M C. 3.6 x10‘4 M D. 0.77 M E. 0.20 M 14. Given a stock solution of 0.250 M KCl, how many mL ofthe stock are needed to make 200 mL ofa 00240 M KCl solution? A. 2.1 mL B. 19.2 mL C. 36.7 mL D. 50.0 mL E. 208 mL 15. Name 3 areas of information found on a MSDS. Physical data, chemical formula, room location. Hazardous ingredients, toxicity, fire hazards. Name of product, spill procedures, preparation procedure. . First aid, explosion data, manufacturer president’s name. All ofthe above. meow? . . . . 7 . 16. You are given an “unknown” containing one or more ofthe three ions Pb2+, Ag: or Hgf. Given the following reactions and observations, identify all ions in solution. sz+ Ag+ and Hgg2+ Pb2+ and Ag+ . Pb2+ and ngy Pb2+ , Ag+ and Hg:2+ mcow> AgClm + 2 anm, <2 Ag(NH3);(,q, + crm) PbClm) + hot H20 <:> szflaq) + 2 crm, Hg2C12(S) + 2 NH3m) c> HgNH2Cl(5) + Hg00) + NHflaq) + crm) Pb” (am + 2 Kim) ----> Pblz (5) Observations: 1. When HCl is added, a white precipitate forms. 2. Hot water is added, and the liquid and remaining solid are separated. 3. Addition of K1 to the liquid phase causes no change to the solution. .4. The remaining solid from step 2 is treated with ammonia. After stirring, a greyish—black solid remains. 5 . After separation ofthe solid and liquid in Step 4, HNO; is added to the liquid phase. A white precipitate is formed. 17. The separation of group A cations in the previous problem was achieved because of differences in the of the ions. solubility oxidation number boiling point mass electrons mcom> 18. The MSDS for a certain chemical lists an “LDSO” of 500 mg/kg. This value refers to the chemical’s: A. corrosion hazard B. volatility C. flammability D. flash point E. toxicity 19. A series of standard solutions ofa weak acid yields the conductivity vs. concentration plot shown below. What is the concentration of the acid in an "unknown" solution if the measured conductivity ofthe (7; unknown is 350 118? 3 5‘ A. -2.5 M g B. 6.3 x 10‘3M g C. 3.5 M 'g D. 22 M 8 E. 3.5 x 10'2M Log Concentration 20. Which one ofthe following substances or species is not a precipitate? A. HgNHZCl B. AgCl C. ngclz D. Pb]2 5- Ag(NH3)2+ 21. A student titrates 20.0 mL ofa 0.105 M oxalic acid dihydrate standard (HZCZO4' ZHZO) with 21 NaOH solution to a phenolphthalein endpoint. 1fthe titration requires 32.45 mL ofthe NaOH, what is the concentration ofthe NaOH solution? A. 0.129 M B. 2.78 M C. 0.193 M D. 3.35 M E. 0.434 M 22. Which ofthe following solutions would have the highest theoretical conductivity? 2.0 x 10'3 M NaCl 3.5 x10'4M KOH 2.0 x 10'3 M 132304 5.0 x 10‘4 M H3PO4 They would all have the same theoretical conductivity. mcow> 23. A primary standard for titrating an unknown basic solution is: A. H2C204'2H30 B.NaOH C. H3804 D. HCl 24. In a titration procedure, the concentration ofa sulfuric acid solution is found to be 0.167 :: 0.00257 M. What is the % Relative Standard Deviation (%RSD) ofthe analysis? A. 0.0237% B. 0.372% C. 0.931% D. 1.54 % E. 2.14 % 25. Why is NaOH nearly impossil‘ 2 to weigh accurately? A. It reacts with light. B. It reacts with most containers. C. It absorbs water from the air. D. It absorbs oxygen from the air. E. It reacts with acid in the air. 3% .m :2 sum 5 oz “.2 Eu mm 5 gm :6 =3. .5 .2 m3 fl: 2: E: a ma 5 3 ma va no a.— .F a 8 5s $3 83 88 $8 :3 sea 5s and 35 5.51 :8 SN D Q m: m: a: 3: m2 a: .m— E «2 =2 5: .5 2% EH .5— c: an A; 50 Em Em Em E E S S S 3 me E 8 8 3 a3 85 85 SN EN EN mg 5 ma Na .5 g x: z: .E A? .5 mm. :m ~< cm 5 RE F : =< E .: mo 01 >9 «E on ma 3“ S S S 3 a. E. E S. m» E «F a E as «2 a: N: we 2: 2: z: 89 a? as «X _ oh am =m 50 < .5 5— 5. on. :2 oz vm mm m E am a. s. S. a. 3. a. a. =. 3a .3. 9% a: 93 ES v.3 9% 3m 3m “.mm 9% as “M .5 cm 3 06 «U =N . :0 _z :0 on .5 > om mm 3 mm NM E a... a Ma S 3 x mm 3; $3 Em in Ex Sh mm m: mm mm h< .U m .m a _< M: 2 E 2 E 2 gm :5 3: 3; ed 2: oz m O z D m 3 a a N. e m <5 <0 dd «3. «Fe. ESEBm 2: .3 2a.? 335 s ...
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This note was uploaded on 04/29/2008 for the course CHEM 136 taught by Professor All during the Fall '03 term at Kettering.

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CHEM-100L [All] Midterm (Fall 03) - CHEM 136 Principles of...

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