Chem 221 Practice Exam Questions And Answers Pass Guaranteed

Showing the proper number of significant figures, write [H+] that corresponds to the physiologiccal pH, which is 7.4? a) 3.98e^(-8)M b) 4e^(-8)M c) 4.0e^(-8)M d) none of the above - Correct Answers c A systematic error... a)cannot be discovered or corrected b)Is known as an indeterminate error c)can be discovered and corrected. d)arises from fluctuations of electricity that affects the instrument - Correct Answersc Precision is... a) How close measured values for a sample are to one another b)How many times a measurement is repeated c) How close a measured value is to the "true" value d) none of the above - Correct Answersa How many liters of 0.100 M HCL would be required to react completely with 5.00 grams of calcium hydroxide? Ca(OH)2 + 2HCL - CaCl2 + 2H2O a) 135 L b) 2.08 L c) 0.135 L d) None of the above - Correct Answersd Which of the following would represent ACCURACY but NOT precision? a) Equally scattered on the bullseye b) Scattered around the two most inner rings c) Scattered in the most inner ring d) Scattered in the left corner of outer most ring - Correct Answersb Police have a hit-and-run case and need to identify the brand of red auto paint. The percentage of iron oxide, which gives paint its red color, was analyzed by two different methods. The results were 43.3 (+/-) 0.3% and 43.6 (+/-) 0.1% with five measurements each. Are the standard deviations "Significantly" different from each other with a 95% confidence level? a) Yes b) No c) Possible d) There is insufficient data - Correct Answersa For the balanced equation shown below, how many moles of Fe3O4 will react with 2.04 moles of CO, to form how many moles of FeO? CO + Fe3O4 - 3FeO + CO2 a) 4.08 & 4.08 moles respectively b) 4.08 & 1.02 moles respectively c) 3.06 & 1.02 moles respectively d) 2.04 & 6.12 moles respectively - Correct Answersd A Nitric Acid bottle has a specific gravity of 1.423, and contains 70.9% HNO3 by weight. What is the molarity of HNO3 in this bottle? - Correct Answers16.0 M A Nitric Acid bottle has a specific gravity of 1.423, and contains 70.9% HNO3 by weight. What is the pH? - Correct Answers-1.204 A Nitric Acid bottle has a specific gravity of 1.423, and contains 70.9% HNO3 by weight. How many mL of this bottle would you use to prepare 0.500 mL of 0.100 M HNO3? - Correct Answers3.13e(-3) mL Cleaning Silver Tarnish (Ag2S) is given by the following reaction with Al. Ag2S + 2Al - Ag + Al2S2 (unbalanced) How many gram sof aluminum would be used to react to remove 0.250 g Ag2S Tarnish? - Correct Answers0.0181 g Al Given the following Ka values, which is the following is the strongest acid? a) HOCl (2.9e -8) b) HClO3 (5.0e2) c) HF (6.6e-4) d) HCN (6.2e-10) - Correct Answersb What is the molar cocn'n of Na(+) in a sol'n that has a pNa of 6.372? (Remember Significant Figures) - Correct Answers4.25e-7 M For the balanced eq, how many moles of Fe3O4 will react with 2.04 moles of CO? CO + Fe3O4 - 3FeO + CO2 a) 4.08 moles b) 1.02 moles c) 3.06 moles d) 2.04 moles - Correct Answersd Calculate the pH of 2.6e-2 M NaOH. Since its a based, 14 - pH a) 1.59 b) 7.00 c) 12.41 d) -1.59 - Correct Answersc Accuracy is .......? a) how many times a measurement is repeated b) how close a measured value is to the "true" value. c) how close measured values for a sample are to one another. d) none of the above - Correct Answersb Chlorine is used by textile manufacturers to bleach cloth. Excess chlorine is destroyed by its reaction with sodium thiosulfate, Na2S2O3: Na2S2O3 + 4 Cl2 + 5 H2O - 2 NaHSO4 + 8 HCl How many moles of Na2S2O3 are needed to react with 0.12 mol of Cl2? a) 0.12 mol b) 0.030 mol c) 7.5e-3 mol d) None of the above - Correct Answersb The degree of freedome used to calculate the confidence interval is: a) the number of data points which are being evaluated b) the number of data points -1