Success in CLS Ch. 12 Laboratory Calculations (60 q.)

33. How many milliliters of a 40% w/v NaOH solution are required to prepare 1.5 L of 2 N NaOH? A. 0.3 B. 3.0 C. 30 D. 300

D. 300

20. How many grams of NaOH are required to prepare 4 L of a 2N solution? A. 40 B. 80 C. 160 D. 320

D. 320

23. How many grams of NaOH are required to prepare 2500 mL of a 4 M solution? A. 40 B. 100 C. 160 D. 400

D. 400

26. What is the normality of a 30%w/v H2SO4 solution? A. 0.31 B. 0.61 C. 3.06 D. 6.12

D. 6.12

7. How many grams of CaCl2 •2H2O must be used to prepare 500 mL of 10% anhydrous CaCl2? A. 33.1 B. 41.3 C. 50.0 D. 66.2

D. 66.2

60. What amount of NaCl (mol wt = 58.5) is needed to obtain 50 mg Cl? A. 19.6mg B. 30.3mg C. 50.0mg D. 82.4mg

D. 82.4mg

46. Convert 30°C to degrees Fahrenheit. A. 4°F B. 10°F C. 49°F D. 86°F

D. 86°F

55. Which of the following correctly states the conditions required in using a colorimetric method based on Beer's law? A. Incident radiation should be mono- chromatic. B. Absorption of light by the solvent must be insignificant in comparison with absorption by the solute (the analyte). C. The solution must be sufficiently dilute to provide a linear relation between absorption and concentration. D. All the above

D. All the above

56. When one of two variable quantities changes as a result of a change in the other, the result is frequently presented in the form of a graph. Which of the following descriptions of a graph is correct? A. Thex-axisisusuallyusedtoplotthe independent variable. B. Different scales may be used for each of the two axes. C. Semilog paper uses a logarithmic scale for one axis and a linear', or Cartesian, scale for the other axis. D. All the above

D. All the above

57. Primary standards used for analytical work should have what property? A. The substance must be available in a form not less than 99.95% pure. B. It should not be hygroscopic. C. It must be a stable substance that can be dried, preferably at 104-110°C. D. All the above

D. All the above

14. In a spectrophotometric procedure that follows Beer's law, the absorbance of a standard solution of concentration 15 mg/dL is 0.50 in a 1-cm cell. The absorbance of the sample solution is 0.62. What is the concentration? A. 0.62mg/mL B. 6.2mol/L C. 12.1 mg/dL D. 18.6mg/dL

D. 18.6mg/dL

41. What is the pH of a 0.2 N acetic acid solution that is 1 % ionized? A. 0.703 B. 1.699 C. 1.703 D. 2.699

D. 2.699

37. How many milliliters of a 5 N HC1 solution are required to prepare 4 L of 10%w/v H C 1 ? A. 219 B. 292 C. 1460 D. 2192

D. 2192

10. Convert 70°F to degrees Celsius. A. 7°C B. 12°C C. 20°C D. 21°C

D. 21°C

58. Which of the following weighs the least? A. 0.1 ng B. 0.01 g C. 1.0 mg D. 1000 pg

A. 0.1 ng

25. How many grams of NaOH are required to prepare 500 mL of a 0.02 N solution? A. 0.4 B. 0.8 C. 4.0 D. 8.0

A. 0.4

49. 125I has a half-life of 60 days. At the end of 180 days, what percent of activity would remain? A. 12.5 B. 25.0 C. 33.3 D. 50.0

A. 12.5

28. A serum calcium level is 8.6 mg/dL. What is the concentration in millimoles per liter? A. 2.2 B. 2.5 C. 4.3 D. 8.6

A. 2.2

2. A calcium standard solution contains 10 mg/dL of calcium. What is its concentra- tion in millimoles per liter? A. 2.5mmol/L B. 5.0mmol/L C. 7.5mmol/L D. lO.Ommol/L

A. 2.5mmol/L

53. A sample of deionized water is found to contain a lead concentration of 0.01 ppm. What is the equivalent concentration expressed as milligrams per deciliter? A. 0.01 B. 0.001 C. 0.0001 D. 0.00001

B. 0.001

5. A solution of NaOH is standardized by titration with 0.100 N HC1. A total of 10.0 mL of NaOH requires 11.25 mL of HC1. What is the normality of the NaOH solution? A.0.100 B. 0.112 C. 0.113 D.1.125

B. 0.112

54. Because of a malfunction, a spectrophotometer is able to show only the percent transmittance (%T) readings on its digital display. Convert 68.0%T to its corresponding absorbance. A. 0.109 B. 0.168 C. 0.320 D. 0.495

B. 0.168

50. How many grams of NaOH are required to prepare 500 mL of a NaOH solution with a pH of 12? A. 0.02 B. 0.2 C. 0.4 D. 2.0

B. 0.2

9. Physiologic saline solution is 0.85% NaCl. What is its osmolarity? A. 0.15 B. 0.29 C. 0.85 D. 8.5

B. 0.29

8. What is the osmolality of a solution containing 5.85 g NaCl and 18 g glucose in 1 kg water? A. 0.2 B. 0.3 C. 0.6 D. 0.9

B. 0.3

11. A 5 N solution is diluted 1:4. The resulting solution is diluted 4:15. What is the concentration in normality of the final solution? A. 0.25 B. 0.33 C. 2.5 D. 3.0

B. 0.33

1. What is the molarity of a solution that contains 18.7 g of KCl in 500 mL? A. 0.1 B. 0.5 C. 1.0 D. 5.0

B. 0.5 A simple and universally applicable method for solving laboratory calculation problems is to read the problem with three questions in mind: 1. What am I given? 2. What do I want? 3. What is the relation between no. 1 and no. 2? Given: the concentration of a solution in terms of grams per 500 mL Want: the concentration in terms of molarity (M) Relation: molarity = moles per liter Calculation: A molar solution is one that contains 1 gram molecular weight (usually called 1 mol) of solute per liter of solution. The gram molecular weight is the sum of the atomic weights. A table of atomic weight is used to determine that the gram molecular weight of KCl = 39 + 35.5 = 74.5 g. Express the concentration of the given solution (18.7 g/500 mL) in terms of grams per liter for easy comparison with molarity (moles per liter). 18.7 g/500 mL = 18.7 g/0.5 L = 37.4 g/L moles = grams / gram molecular weight moles = 37.4/74.5 = 0.50 0.50 mol/L = 0.50 M A solution that contains 18.7 g KCl/500 mL is 0.50 M KCl.

3. How much NaCl is needed to prepare 100 mL of a standard solution of concentration 135mEq/L of Na? A. 0.31g B. 0.79g C. 1.2g D. 1.8g

B. 0.79g

30. With the use of concentrated HC1 (sp.gr. = 1.19 g/mL; assay = 37.5%), 3 L of 0.50 N HC1 are prepared. A total of 16 mL of 0.20 N NaOH is required to titrate 7 mL of the HC1 solution, indicating a lower normality of the acid solution than desired. How many milliliters of concentrated HC1 must be added to the acid solution to attain an accurate 0.50 N HC1 solution? A. 6.40 B. 10.53 C. 101.03 D. 105.33

B. 10.53

39. An analysis for sodium is performed on an aliquot of a 24-hour urine specimen. A sodium value of 122.5 mmol/L is read from the instrument. What is the amount of sodium in the 24-hour urine specimen if 1540 mL of urine are collected? A. 79.5 B. 188.6 C. 1886.5 D. 18,865

B. 188.6

29. How many milliliters of concentrated HNO3 (sp. gr. = 1.42 g/mL; assay = 70%) are required to prepare 2 L of 0.15 N HNO3? A. 13.3 B. 19.0 C. 38.0 D. 189.9

B. 19.0

38. A serum potassium level is 19.5 nig/dL. What is the concentration in milliequiva- lents per liter? A. 0.5 B. 5.0 C. 10.0 D. 19.5

B. 5.0

44. An enzyme assay is performed at 37°C, and absorbance readings are taken each minute for a total of 4 minutes. Given the following information (See book for table), what is the enzyme activity in units per liter at 37°C? A. 490 B. 522 C. 525 D. 1307

B. 522

51. What is the relative centrifugal force (X g) of a centrifuge operating at 2500 rpm with a radius of 10 cm? A. 625 B. 699 C. 1250 D. 6988

B. 699

48. Each radionuclide has a unique half-life associated with it. Assuming an initial activity of 100%, through how many half- life periods must a nuclide pass to bring its activity down to less than 1%? A. 3 B. 7 C. 10 D. 100

B. 7

13. A solution of a colored substance that is known to follow Beer's law has an absorbance of 0.085 when measured in a cell 1 cm in length. Calculate the absorbance for a solution of twice the concentration measured in the same cell. A. 0.042 B. 0.085 C. 0.170 D. 5.90

C. 0.170

42. What is the ionic strength of a 0.2 M Na2SO4 solution? A. 0.4 B. 0.5 C. 0.6 D. 1.2

C. 0.6

32. How many milliliters of a stock solution of 20%w/v NaOH are required to prepare 800 mL of a 2.5%v/v solution? A. 20 B. 50 C. 100 D. 125

C. 100

34. How many grams of anhydrous sodium sulfate (mol wt = 142) are required to prepare 750 mL of a 23%w/v solution? A. 2.3 B. 106.5 C. 172.5 D. 230

C. 172.5

18. A quantitative protein analysis is performed on an aliquot of a 24-hour urine specimen. The test indicates the presence of 1.2%protein. If a total urine volume of 2155 mL is collected,how many grams of protein are excreted in the 24-hour specimen? A. 0.056 B. 2.6 C. 25.9 D. 258.6

C. 25.9

6. How many milliliters of concentrated H2SO4 (sp. gr. = 1.84 g/mL; assay = 97%) are required to prepare 10 L of 0.1 N H2SO4? A. 1.84 B. 9.20 C. 27.5 D. 54.4

C. 27.5

4. How much 95% alcohol is required to prepare 5 L of 70% alcohol? A 2.4 L B. 3.5 L C. 3.7 L D.4.4 L

C. 3.7 L

47. A curie (Ci) is the quantity of radioactive material that exhibits A. 3.7 X 104dps B. 3.7 X 107dps C. 3.7 X 1010dps D. 3.7 X 1010dpm

C. 3.7 X 1010dps

17. How many grams of sulfosalicylic acid (mol wt = 254) are required to prepare 1 L of a 3% w/v solution? A. 3.0 B. 7.6 C. 30 D. 254

C. 30

15. A stock standard solution of urea contains 10 mg/mL of urea nitrogen. How much stock (in milliliters) is needed to prepare 200 mL of a working standard containing 20 mg/dL of urea nitrogen? A. 1 B. 2 C. 4 D. 8

C. 4

36. A serum calcium level is 8.6 mg/dL. What is the concentration in milliequivalents per liter? A. 2.2 B. 2.5 C. 4.3 D. 8.6

C. 4.3

24. An isotonic saline solution contains 0.85%w/v NaCl. How many grams of NaCl are needed to prepare 5 L of this solution? A. 4.25 B. 8.5 C. 42.5 D. 170

C. 42.5

35. With the use of concentrated HC1, 2 L of 0.20 N HC1are prepared. On titration, it is determined that the normality is actually 0.208. To correct this error, how many milliliters of deionized water must be added to the solution (10 mL used in titration process) to make an accurate 0.20 N HC1solution? A. 10.4 B. 76.5 C. 79.6 D. 80.0

C. 79.6

45. A patient weighs 175.5 pounds. What is the patient's weight expressed in kilograms? A. 8.0 B. 38.6 C. 79.8 D. 87.8

C. 79.8

59. The OH- concentration of a solution is 1 X 10^-6. What is the pH of this solution? A. 0.6 B. 6 C. 8 D. 14

C. 8

52. A 10-mL class A volumetric flask has an accuracy of ±0.2%. Express the ±0.2% tolerance in terms of milliliters. A. ±0.002 B. ±0.01 C. ±0.02 D. ±0.04

C. ±0.02

40. With the use of concentrated HNO3, 4 L of 0.50 N HNOs are prepared. On titration, it is determined that the normality is actually 0.513. To correct this error, how many milliliters of deionized water must be added to the remaining 3.975 L of solution to make an accurate 0.50 N HNO3 solution? A. 25.6 B. 100.7 C.103.4 D. 104.0

C.103.4

12. A colorimetric method calls for the use of 0.1 mL of serum, 5 mL of reagents, and 4.9 mL of water. What is the dilution of the serum in the final solution? A. I to 5 B. 1 to 10 C. I to 5O D. 1 to 100

D. 1 to 100

43. A 1.0 mg/dL bilirubin standard (purity = 99.0%; mol wt = 584) is prepared by dissolving it in chloroform at 25°C. Under these conditions, the molar absorptivity at 453 nm is 60,700. What is the expected absorbance of this standard solution? A. 0.104 B. 0.607 C. 0.962 D. 1.039

D. 1.039

16. How many milliliters of a 50%v/v acetic acid solution are required to prepare 1 L of 5 %v/v acetic acid? A. 0.01 B. 0.10 C. 10 D. 100

D. 100

21. How many milliliters of glacial acetic acid (mol wt = 60; assay = 99.7%) are required to prepare 2 L of a 5%v/v solution? A. 6 B. 10 C. 50 D. 100

D. 100

27. A serum chloride concentration is 369 mg/dL. What is the concentration in milliequivalents per liter? A. 5 B. 10 C. 36 D. 104

D. 104

31. A serum chloride concentration is 369 mg/dL. What is the concentration in millimoles per liter? A. 5 B. 10 C. 36 D. 104

D. 104

19. How many grams of H2SO4 are required to prepare 750 mL of a 2M solution? A. 36.8 B. 73.5 C. 98 D. 147

D. 147

22. How many grams of H2SO4 are required to prepare 6 L of a 5 N solution? A. 245 B. 294 C. 490 D. 1470

D. 1470