Module 8: Practice Problems 1. Convert a blood plasma level range of 5 to 20 µg/ml of tobramycin (Z = 467.52) to µmol/l. 5 µg/ml = 10.7 µmol/l 20 µg/ml = 42.8 µmol/l 2. A preparation contains in each milliliter, 236 mg of dibasic potassium phosphate (Z = 174.18) and 224 mg of monobasic potassium phosphate (Z = 136.09). Calculate the total concentration of phosphorus, in mmol/ml, in the preparation. Answer: 3.001 mmol/ml 3. A 10-mL ampul of potassium chloride contains 2.98 g of KCl. What is the concentration of the solution in terms of milliequivalents per milliliter? Answer: 4 meq/ml 4. A person is to receive 36 mg of ammonium chloride per kilogram of body weight. If the person weighs 154 lb, how many milliliters of a sterile solution of ammonium chloride (NH4Cl, Z = 53.5) containing 0.4 meq/ml should be administered? Answer: 117.76 milliliters (ml) 5. A sterile solution of potassium chloride (KCl) contains 2 meq/ml. If a 20-mL ampul of the solution is diluted to 1 liter with SWFI, what is the percentage strength of the resulting solution? Answer: 0.298% (w/v) 6. A certain electrolyte solution contains, as one of the ingredients, the equivalent of 4.6 meq of calcium per liter. How many grams of calcium chloride (CaCl2 H2O, Z = 147) should be used in preparing 20 liters of the solution? Answer: 6.762 grams (g) 7. Sterile solutions of ammonium chloride containing 21.4 mg/ml are available commercially in 500- and 1000-mL IV infusion containers. Calculate the amount, in terms of meq, of ammonium chloride (NH4Cl, Z = 53.5) in the 500-mL container. Answer: 200 meq 8. A solution contains, in each 5 ml, 0.5 g of potassium acetate (C2H3KO2, Z = 98), 0.5 g of potassium bicarbonate (KHCO3, Z = 100), and 0.5 g of potassium citrate (C6H5K3O7 H2O, Z = 324). How many milliequivalents of potassium (K + ) are represented in each 5 ml of the solution? Answer: 14.73 meq 9. How many grams of sodium chloride (NaCl) should be used in preparing 20 liters of a solution containing 154 meq/l? Answer: 180.18 grams (g) 10. Sterile solutions of potassium chloride (KCl) containing 5 meq/ml are available in 20-mL containers. Calculate the amount, in grams, of potassium chloride in the container. Answer: 7.45 grams (g) 11. How many milliliters of a solution containing 2 meq of potassium chloride (KCl) per milliliter should be used to obtain 2.98 g of potassium chloride? Answer: 20 milliliters (ml) 1
12. A patient is given 125 mg of phenytoin sodium (C15H11N2NaO2, Z = 274) three times a day. How many milliequivalents of sodium are represented in the daily dose? Answer: 1.37 meq 13. A 40-mL vial of sodium chloride solution was diluted to 1 liter with sterile distilled water. The concentration (w/v) of sodium chloride (NaCl) in the finished product was 0.585%. What was the concentration, in milliequivalents per milliliter, of the original solution? Answer: 2.5 meq/ml 14. How many grams of sodium bicarbonate (NaHCO3, Z = 84) should be used in preparing a liter of a solution to contain 44.6 meq per 50 ml? Answer: 74.928 grams (g) 15. A solution contains 20 mg% (20 mg/100 ml) of Ca +2 ions. Express this concentration in terms of milliequivalents per liter. Answer: 10 meq/l 16. A sterile sodium lactate solution is available commercially as a 1 /6-molar solution of sodium lactate (C3H5NaO3, Z = 112). How many meq of sodium lactate would be provided by a liter of the solution? Answer: 166.67 meq 17. A certain electrolyte solution contains 0.9% NaCl in 10% dextrose solution. Express the concentration of NaCl in terms of meq/l. Answer: 153.85 meq/l 18. Consider the following prescription: Potassium chloride 10% Cherry syrup ad 480 ml Sig. Tbsp PO BID How many milliequivalents of potassium chloride are represented in each prescribed dose? Answer: 20.13 meq 19. How many milliequivalents of potassium are in 5 million units of penicillin V potassium (C16H17KN2O6S, Z = 388)? One milligram of penicillin V potassium represents 1380 units. Answer: 9.34 meq 20. The normal potassium level in blood plasma is 17 mg% (17 mg/100 ml). Express this concentration in terms of milliequivalents per liter. Answer: 4.36 meq/l 21. How many grams of potassium citrate (C6H5K3O7 H2O, Z = 324) should be used in preparing 500 ml of a potassium ion elixir so as to supply 15 meq of K + in each 5-mL dose? Answer: 162 grams (g) 22. A potassium supplement tablet contains 2.5 g of potassium bicarbonate (KHCO3, Z = 100). How many milliequivalents of potassium (K + ) are supplied by the tablet? Answer: 25 meq 2
23. Ringer s injection contains 0.86% of sodium chloride, 0.03% of potassium chloride, and 0.033% of calcium chloride. How many milliequivalents of each chloride are contained in 1 liter of the injection? From NaCl = 147 meq From KCl = 4.03 meq From Ca2Cl = 4.49 meq Total = 155.52 meq 24. Calculate the sodium (Na + ) content, in terms of milliequivalents, of 1 g of ampicillin sodium (C16H18N3NaO4S, Z = 371). Answer: 2.695 meq 25. A 20-mL vial of concentrated ammonium chloride solution containing 5 meq/ml is diluted to 1 liter with sterile distilled water. a. Calculate the total milliequivalent value of the ammonium ion in the dilution. Answer: 100 meq b. Calculate the percentage strength of the dilution. Answer: 0.535% (w/v) 26. Ringer s solution contains 0.33 g of calcium chloride per liter. Express the concentration in terms of milliequivalents of calcium chloride (CaCl2 2H2O, Z = 147) per liter. Answer: 4.49 meq/l 27. How many milliequivalents of potassium would be supplied daily by the usual dose (0.3 ml TID) of saturated potassium iodide solution? Saturated potassium iodide solution contains 100 g of potassium iodide per 100 ml. Answer: 5.42 meq 28. An intravenous solution calls for the addition of 25 meq of sodium bicarbonate. How many milliliters of 8.4% w/v sodium bicarbonate injection should be added to the formula? Answer: 25 milliliters (ml) 29. Calcium gluconate (C12H22CaO14, Z = 430) injection 10% is available in a 10-mL ampul. How many milliequivalents of Ca +2 does the ampul contain? Answer: 4.65 meq 30. A flavored potassium chloride packet contains 1.5 g of potassium chloride. How many milliequivalents of potassium chloride are represented in each packet? Answer: 20.13 meq 31. How many milliequivalents of Li + are provided by a daily dose of four 300-mg tablets of lithium carbonate (Li2CO3, Z = 74)? Answer: 32.43 meq 32. How many milliequivalents of ammonium (NH4 + ) ion are contained in 1 liter a 4.2% w/v solution of ammonium chloride? Answer: 785.05 meq 3
33. A patient is to receive 10 meq of potassium gluconate (C6H11KO7, Z = 234) four times a day for 3 days. If the dose is to be 1 tsp in a cherry syrup vehicle, a. How many grams of potassium gluconate should be used? Answer: 28.08 grams (g) b. What volume, in milliliters, should be dispensed to provide the prescribed dosage regimen? Answer: 60 milliliters (ml) 34. A physician wishes to administer 1,200,000 units of penicillin G potassium every 4 hours. If 1 unit of penicillin G potassium (C16H17KN2O4S, Z = 372) equals 0.6 µg, how many milliequivalents of K + will the patient receive in a 24-hour period? Answer: 11.613 meq 35. Five milliliters of lithium citrate syrup contain the equivalent of 8 meq of Li +. Calculate the equivalent, in milligrams, of lithium carbonate (Li2CO3, Z = 74) in each 5-mL dose of the syrup. Answer: 296 milligrams (mg) 36. How many milligrams of magnesium sulfate (MgSO4, Z = 120) should be added to an IV solution to provide 5 meq of Mg +2 per liter? Answer: 300 milligrams (mg) 37. K-tab, a slow-release potassium chloride tablet, contains 750 mg of potassium chloride in a wax/polymer matrix. How many milliequivalents of potassium chloride are supplied by a dosage of 1 tab PO TID? Answer: 30.2 meq/day 38. An electrolyte solution contains 222 mg of sodium acetate (C2H3NaO2, Z = 82) and 15 mg of magnesium chloride (MgCl2, Z = 95) in each 100 ml. Express these concentrations in milliequivalents of Na + and Mg +2 per liter. Na + = 27.07 meq/l Mg + = 3.16 meq/l 39. Ammonium chloride (NH4Cl, Z = 53.5) is to be used as a urinary acidifier with a dose of 150 meq. How many 500-mg tablets should be administered? Answer: 16 tablets (closest to dose) 40. A patient has a sodium deficit of 168 meq. How many milliliters of isotonic NaCl solution should be administered to replace the deficit? Answer: 1092 milliliters (ml) 41. A normal 70 kg (154 lb) adult has 80 to 100 g of sodium in their body, primarily contained in the extracellular fluid. Body retention of an additional 1 g of sodium results in excess body water accumulation of approximately 310 ml. If a person contains 100 meq of extra sodium, how many milliliters of additional water could be expected to be retained? Answer: 713 milliliters (ml) 4
42. A patient receives 3 liters of an electrolyte fluid containing 234 mg of sodium chloride (Z = 58.5), 125 mg of potassium acetate (C2H3KO2, Z = 98), and 21 mg of magnesium acetate (C4H6MgO4, Z = 142) per 100 ml. How many milliequivalents each of Na +, K +, and Mg +2 does the patient receive? Na + = 120 meq K + = 38.27 meq Mg + = 8.87 meq 43. How many milliliters of a 2% w/v solution of ammonium chloride (NH4Cl, Z = 53.5) should be administered intravenously to a patient to provide 75 meq? Answer: 200.625 ml 44. The usual adult dose of calcium for elevating serum calcium is 7 to 14 meq. How many milliliters of calcium gluceptate injection, each milliliter of which provides 18 mg of elemental calcium, would provide the recommended dosage range? Answer: 7.778 ml to 15.556 ml 45. The oral pediatric maintenance solution Pedialyte liquid has the following electrolyte content per liter: 45 meq of sodium, 20 meq of potassium, 35 meq of chloride, 30 meq of citrate. Calculate the equivalents quantities of each in terms of milligrams. Na + = 1035 milligrams (mg) K + = 780 milligrams (mg) Cl - = 1242.5 milligrams (mg) Citrate = 1890 milligrams (mg) 46. Calculate the milliequivalents of chloride per liter of the following parenteral fluid: Sodium chloride 516 mg Potassium chloride 89.4 mg Calcium chloride, anhydrous 27.8 mg Magnesium chloride, anhydrous 14.2 mg Sodium lactate, anhydrous 560 mg SWFI ad 100 ml Answer: 108.21 meq 47. The pediatric infusion rate for potassium is 5 meq/hour. If 9 ml of a 39.2% solution of potassium acetate (KC2H3O2) is diluted to 1 L of infusion solution, calculate the proper infusion rate in ml/hr. Answer: 138.89 ml/hr 48. Colyte, a colon lavage preparation contains the following mixture of dry powder to prepare 4 liters of solution: Sodium chloride 5.84 g Potassium chloride 2.98 g Sodium bicarbonate 6.72 g Sodium sulfate, anhydrous 22.72 g Polyethylene glycol 3350 240 g Calculate the milliequivalents each of sodium and chloride present per liter of prepared solution. Sodium (Na + ) = 124.957 meq/l Chloride (Cl - ) = 34.957 meq/l 5
49. At 3:00 pm, a pharmacist received an order to add 30 meq/l of potassium chloride to the already running IV fluid for a patient. After checking the med order, the pharmacist found that the patient is receiving D5W in NS infusion at a rate of 85 ml/hour, and that the patient s liter of fluid was started at 1:30 pm. a. Assuming that it took 30 minutes to provide the needed potassium chloride to the floor nurse, how many milliequivalents of potassium chloride should have been added to the patient s running IV fluid to achieve the ordered concentration? Answer: 24.9 meq b. How many milliliters of an injection containing 2 meq of potassium chloride per ml should have been used to supply the amount of potassium chloride needed? Answer: 12.45 milliliters (ml) c. What was the osmolality of the infusion with the potassium chloride added? Assume the complete dissociation of the NaCl and KCl. Answer: 645.57 mosmol/l 50. A solution contains 322 mg of Na + ions per liter. How many milliosmoles are represented in the solution? Answer: 14 mosmol 51. How many milliosmoles of sodium are represented in 1 liter of 3% hypertonic NaCl solution? Assume complete dissociation. Answer: 512.82 mosmol 52. A solution of sodium chloride contains 77 meq/l. Calculate its osmolar strength in terms of milliosmoles per liter. Assume complete dissociation. Answer: 154 mosmol/l 53. Calculate the osmolar concentration, in terms of milliosmoles, represented by 1 liter of a 10% w/v solution of anhydrous dextrose (Z = 180) in water. Answer: 555.56 mosmol/l 54. Calculate the osmolarity, in milliosmoles per milliliter, of a parenteral solution containing 2 meq/ml of potassium acetate (KC2H3O2, Z = 98). Answer: 4 mosmol/ml 55. Given a 500-mL parenteral fluid containing 5% w/v sodium bicarbonate, a. Calculate milliequivalents per milliliter Answer: 0.595 meq/ml b. Calculate total milliequivalents Answer: 297.62 meq c. Calculate osmolarity Answer: 1,190.48 mosmol/l 6
56. What is the osmolarity of an 8.4% w/v solution of sodium bicarbonate? Answer: 2,000 mosmol/l 57. A hospital medication order calls for the administration of 100 g of mannitol to a patient as an osmotic diuretic over a 24- hour period. Calculate a. how many milliliters of a 15% w/v mannitol injection should be administered per hour Answer: 27.78 milliliters (ml) b. how many milliosmoles of mannitol (Z = 182) would be represented in the prescribed dosage. Answer: 549.45 mosmol (in a 24-hour period) 58. In 147 ml of a 10% w/v calcium chloride (CaCl2 H2O, Z = 147) solution a. there are how many millimoles of calcium chloride? Answer: 100 mmol b. there are how many milliequivalents of calcium chloride? Answer: 200 meq c. there are how many milliosmoles of calcium chloride? Answer: 300 mosmol 59. Calculate the daily water requirement for a healthy adult weighing 165 lb. Using weight based range: 1,500 ml to 2,625 ml Using formula: 2,600 ml 60. Estimate the plasma osmolality, in milliosmoles per kilogram, from the following data: Sodium 136 meq/l Potassium 5 meq/l BUN 26 mg/100 ml Glucose 90 mg/dl Answer: 296.286 mosmol 7