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1.1: Introductory Principles

  • Page ID
    113848
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    1. A stock solution of NaOH is exactly 12.0 M. How many ml of the stock solution would you use to prepare one liter of a 3% weight/volume solution? (MW NaOH = 40 gm/mmol)?
      1. 833 mL
      2. 625 mL
      3. 62.5 mL
      4. 6.25 mL
      5. 83.3 mL
    2. How many ml of concentrated HC1 (sp. gr. = 1.20; 30% purity) would be needed to prepare one liter of a 4 M solution (atomic weight H = 1; Cl = 35)?
      1. 72 mL
      2. 86.4 mL
      3. 144 mL
      4. 200 mL
      5. 400 mL
    3. The pH of a 0.1 M solution of HCl is
      a. 1
      b. 3.5
      c. 4
      d. 6
      e. 7
    4. If a patient has a serum calcium concentration of 5.0 mEq/L, what is this value in mg/dL (atomic weight of Ca = 40.08)?
      1. 1 mg/dL
      2. 10 mg/dL
      3. 20 mg/dL
      4. 100 mg/dL
      5. 200 mg/dL
    5. How would you prepare 3 liters of 6N H2SO4 solution from the concentrated acid available? (Sp. Gr. = 1.84, 100% purity Mol. Weight H2SO4 = 98)
      1. take 239 mL acid and dilute to 3 liters
      2. take 441 mL acid and dilute to 3 liters
      3. take 479 mL acid and dilute to 3 liters
      4. take 882 mL acid and dilute to 3 liters
      5. take 958 mL acid and dilute to 3 liters
    6. You will be performing a calcium/ magnesium analysis by the atomic absorption spectrophotometer. The procedure does not specify the type of water to be used for preparing reagents. What would be the best choice of water?
      1. double distilled
      2. type I water
      3. type III water
      4. type II water
      5. filtered with a 0.22 \(\mu\)pore filter
    7. A buffer can be defined as:
      1. a strong acid plus a strong base
      2. a weak acid plus the salt of the acid
      3. a strong acid plus the salt of the acid
      4. a salt solution
    8. The pH of a solution composed of 0.4 M HA (Ka dissoc. = 2.0 x 10-6) and 0.2 M NaA is:
      1. 2.7
      2. 3.0
      3. 5.4
      4. 6.0
      5. 6.8
    9. The total concentration of a buffer (HA + A-) is 0.275 mol/L. The concentration of the weak acid is 0.025 mol/L, and its dissociation constant is 10-6 mol/L. What is the pH of this solution?
      1. 4
      2. 5
      3. 6
      4. 7
      5. 8
    10. The pH of a buffer solution is 6.5. The pKa of the buffer is 7.5. If the total concentration of the buffer (HA + A-) is 10 mmol/L, what is the concentration of the conjugate base?
      1. 0.0909 mmol/L
      2. 0.909 mmol/L
      3. 9 mmol/L
      4. 90.9 mmol/L
      5. 4.45 mmol/L
    11. In a 1 to 5 dilution of 2.4 M NaOH, the final concentration is:
      1. 0.40 M
      2. 0.040 M
      3. 0.48 M
      4. 0.048 M
      5. 0.50 M
    12. The molecular weight of glucose is 180 g/mol. A 3600 mg/L solution
      1. 40 mM
      2. 20 mM
      3. 400 mM
      4. 200 mM
      5. 2 mM
    13. 10.0 mL of 0.5 M HC1 was used to titrate 5.0 mL of NaOH to its equivalence point. The molarity of the NaOH is:
      1. 0.5
      2. 2.0
      3. 1.0
      4. 0.1
      5. 0.2
    14. 100 mg of CaCl2 was made up to 25 mL. The calcium concentration of the solution is:
      1. 100 mg/dL
      2. 400 mg/dL
      3. 40 mg/dL
      4. 10 mg/dL
      5. 50 mg/dL
    15. A sodium concentration is reported as 326 mg/dL. The concentration expressed in mEq/L is: (atomic weight Na is 23):
      1. 100
      2. 128
      3. 142
      4. 150
      5. 185
    16. In a total protein analysis where the color follows Beer’s Law, a patient’s serum had an absorbance of 0.300 at 540nm; a 5.0 g/L standard had an absorbance of 0.250 at 540 nm, the patient’s protein concentration is:
      1. 4.2 g/L
      2. 6.0 g/L
      3. 3.0 g/L
      4. 9.0 g/L
      5. 3.6 g/L
    17. 100 mg of CaCl2 \(\cdot\) 2H2O was made up to 500 mL. The atomic weight of Ca = 40, Cl = 35.5, H = 1, O = 16. The calcium concentration of the solution is:
      1. 100 mg/dL
      2. 5.4 mg/dL
      3. 27 mg/dL
      4. 54 mg/dL
      5. 10 mg/dL
    18. The atomic weight of magnesium is 24 g/mol. A 360 mg/L solution of magnesium is:
      1. 1.5 mM
      2. 2.0 mM
      3. 0.67 mM
      4. 0.15 mM
      5. 15 mM
    19. In a four-fold serial dilution, the undiluted specimen is in tube #1. What is the dilution in tube #5?
      1. 1:16
      2. 1:32
      3. 1:64
      4. 1:128
      5. 1:256
    20. How much sodium sulfate must be weighed out to prepare 300 mL of a 25% w/v solution? (Mol. Weight: Na2SO4 = 142).
      1. 19.9 g
      2. 25 g
      3. 75 g
      4. 166 g
      5. 498 g
    21. How many mL of a 5 M solution would be needed to make 250 mL of a 2 M solution?
      1. 20 mL
      2. 40 mL
      3. 62.5 mL
      4. 100 mL
      5. 625 mL
    22. You need to prepare 500 mL of a dilute glucose standard (200 mg/L) from a stock standard (2500 mg/L). How much of the stock standard would you need?
      1. 5 mL
      2. 10 mL
      3. 20 mL
      4. 40 mL
      5. 80 mL
    23. How much CaSO4 (Ca = 40; S=32; O =16) should be weighed out to prepare one liter of a 0.5 M solution of CaSO4?
      1. 6.8 g
      2. 13 g
      3. 27.2 g
      4. 34 g
      5. 68 g
    24. A tube contains the following: Serum 0.25 mL, Saline 0.75 mL. Antigen 1 mL. What is the serum dilution?
      1. 1:2
      2. 1:4
      3. 1:7
      4. 1:8
      5. 1:16
    25. Find the weight of Na2SO4 \(\cdot\) 7H2O that must be used to prepare 200 mL of a 25% solution of Na2SO4. Atomic weight: H = 1, Na = 23, S = 32, O = 16).
      1. 62 g
      2. 94 g
      3. 116 g
      4. 256 g
      5. 173 g

    Use the following key to answer questions 26 through 31:

    1. 1,2, and 3 are correct
    2. 1 and 3 are correct
    3. 2 and 4 are correct
    4. only 4 is correct
    5. all are correct
    1. Which of the following statements about laboratory water are true?:
      1. Reagent grade water is obtained from Type III water which has been
        polished with activated carbon, ion exchange resins, and a bacterial filter
      2. Laboratory grade water is obtained by pumping tap water through a
        selectively permeable membrane
      3. Distillation removes organic impurities while deionization removes inorganic
        impurities
      4. Steam from boiled water is cooled and collected to make Type I water.
    2. Volumetric pipets are used for which of the following situations?
      1. to pipet 2 mL saline for serial dilutions
      2. to pipet 5 mL of stock standard solution into a volumetric flask
      3. to pipet 2 mL of blood for a chromatographic extraction
      4. to pipet 0.5 mL solution from a 1 mL pipet
    3. Volumetric flasks are:
      1. used for approximate quantities
      2. not to be used for quantities below 100 mL
      3. used with refrigerated or non-refrigerated solutions
      4. never used as storage bottles
    4. TC on a pipet means “TO CONTAIN”. This pipet should be:
      1. blown out only
      2. drained only
      3. used only to deliver solution between two calibration marks on the pipet
      4. rinsed after delivery
    5. Pyrex laboratory glassware:
      1. is six times stronger than regular borosilicate
      2. has alkaline metals for strength
      3. is known for its heat and thermal shock resistance
      4. is made of over 96% silica giving it quartz-like qualities
    6. You are asked to make reagents for and run a new procedure. You have decided to use a reagent that is labeled PG or practical grade that is on the Chemistry Lab’s stock shelves. When you have completed the test, the control values are too high. What should you do?:
      1. run the test again with a reagent blank vs. a water blank
      2. look for a chemical that is labeled “Technical Grade” and remake the reagent
      3. send out the results in spite of the control values since many times controls do not match hen new reagents are used
      4. remake the reagent with USP or NBS grade chemicals
    7. Safety regulations in the clinical laboratory fall under which government agency?
      1. Centers for Disease Control
      2. Food and Drug Administration
      3. National Institute of Laboratory Sciences
      4. Occupational Safety and Health Administration
      5. College of American Pathologists
    8. Gas Cylinders are securely fastened (chained, etc.) because:
      1. they are valuable and may be stolen.
      2. this prevents them from tipping over.
      3. this prevents the valves from shaking loose.
      4. this secures them in a known place
      5. the gas can be better controlled
    9. Universal precautions require that:
      1. all infectious material be labeled.
      2. all potentially infectious material be labeled.
      3. all body fluids be treated with equal precautions.
      4. serum and blood products must be separated.
      5. all body fluids must be labeled carefully.
    10. A vaccine is not available for which of the following infectious agents commonly encountered by laboratory personnel?
      1. hepatitis B
      2. human immunodeficiency virus
      3. polio virus
      4. influenza virus
      5. pneumonia virus

    Use the following key to answer questions 36 and 37.

    1. 1,2, and 3 are correct
    2. 1 and 3 are correct
    3. 2 and 4 are correct
    4. only 4 is correct
    5. all are correct
    1. Mercury (Hg) used in the laboratory can be toxic by:
      1. contact of liquid Hg
      2. ingestion of liquid Hg
      3. breathing of volatile Hg fumes
      4. reaction with atmospheric O2 to form combustible material
    2. The following data should be obtained from a centrifuge for quality control of the instrument’s maintenance.
      1. nomogram RCF
      2. nominal RCF
      3. maximum g force
      4. revolutions per minute

    Use the same key to answer questions as in questions 36 and 37.

    1. Elements of the Chemical Hygiene Plan include:
      1. Maintaining health records for 30 years after an employee terminates employment
      2. Maintaining copies of MSDSs in the laboratory director’s office
      3. The provision of personal protective equipment by the employer
      4. Storing chemicals in a single area, regardless of the toxicity
    2. Safety practices in the laboratory include:
      1. The lack of need to use safety glasses if corrective lenses are worn
      2. Not wearing contact lenses in the laboratory since they prevent proper washing of the eyes in the event of a spill
      3. Allowing sandals to be worn in the summer
      4. Flushing the eyes for 15 minutes in the event of contact with chemicals
    3. When considering latex allergy:
      1. There is no concern regarding the development of respiratory symptoms in some cases
      2. Powder-free latex gloves are safe to use for workers with latex allergy
      3. The allergy comes from the latex itself and never from the chemicals added to the latex during harvesting
      4. Latex proteins can be adsorbed onto the powder that is used on many gloves
    4. The requirements for operation of an electronic balance include:
      1. Placement in a vibration-free location
      2. Placement by a sunny window to ensure good lighting
      3. Verification of the optical zero
      4. Placement under an air conditioning vent to ensure a cool temperature
    5. Volumetric flasks:
      1. Should not be used as storage containers
      2. Contain an exact volume when filled to indicator line
      3. Are calibrated to be used at the temperature specified on the flask
      4. Can be used as transfer devices to deliver an exact amount of fluid
    Answer
    1. c (p. 35-36)
    2. e (p. 36-37)
    3. a (p. 39)
    4. b (p. 35-36)
    5. c (p. 34-36)
    6. b (p. 7)
    7. b (p. 38-39)
    8. b (p. 39)
    9. d (p. 39)
    10. b (p. 39)
    11. c (p. 34-35)
    12. b (p. 36-37)
    13. c (p. 35)
    14. b (p. 35-36)
    15. c (p. 35-36)
    16. b (p. 37-38)
    17. b (p. 36-37)
    18. e (p. 36-37)
    19. e (p. 34-35)
    20. c (p. 35)
    21. d (p. 34)
    22. d (p. 34)
    23. e (p. 35-37)
    24. d (p. 34)
    25. b (p. 35-37)
    26. a (p. 5-6)
    27. a (p. 14,17)
    28. d (p. 13)
    29. d (p. 14)
    30. d (p. 10)
    31. d (p. 9)
    32. d (p. 26)
    33. c (p. 28)
    34. c (p. 31-33)
    35. b (p.33)
    36. a (p. 30)
    37. d (p. 24-25)
    38. b (p. 27-29)
    39. d (p. 28)
    40. d (p. 33-34)
    41. b (p. 21-22)
    42. a (p. 13)

    This page titled 1.1: Introductory Principles is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Lawrence Kaplan & Amadeo Pesce.

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