Milliequivalents

David is preparing a solution that contains 10 mg/100mL of K⁺ ions. Express the concentration of this solution in terms of mEq/L. MW of K⁺= 39.

• 0.256 mEq/L

• 3.200 mEq/L

• 1.500 mEq/L

• 2.564 mEq/L

Zoe is preparing a stock electrolyte solution. She needs to find out the concentration in g/mL of the solution containing 4 mEq of calcium chloride (CaCl₂·2H₂O) per mL. MW of CaCl₂·2H₂O = 40(Ca++) + [2x35.5(Cl-)] + [2x18(H₂O)] = 147.

• 0.147 g/mL

• 0.588 g/mL

• 0.735 g/mL

• 0.294 g/mL

A magnesium (Mg++) level in plasma is 2.5 mEq/L. Express this concentration in terms of mg/L.

MW Mg++ = 24.

• 30 mg/L
• 45 mg/L
• 75 mg/L
• 60 mg/L

How many mEq of Mg++ are represented in an 8 mL dose of an injectable solution containing 50% w/v MgSO4 heptahydrate? MW = 24(Mg++) + 96(SO₄^2-) + [7x18] = 246.

• 8.12 mEq

• 24.50 mEq

• 12.75 mEq

• 16.26 mEq

• 32.52 mEq

Answer explanation

To find mEq of Mg++, calculate the amount of MgSO4 in 8 mL of 50% w/v solution. 50% w/v means 50 g in 100 mL, so in 8 mL, there are 4 g = 4000 mg; Mg valence = 2.

Convert mg to mEq: (4000 mg *2)/246 mg = 32.52 mEq.

An injectable solution contains 30% w/v of KCl. How many mEq of K⁺ are in a 5 mL dose? MW = 39(K⁺) + 35.5(Cl^-) = 74.5.

• 20.13 mEq

• 40.26 mEq

• 60.39 mEq

• 80.52 mEq

Answer explanation

To find mEq of K+ (valence = 1) calculate the amount of KCl in 5 mL: 30% w/v means 30 g in 100 mL, so in 5 mL, it's 1.5 g or 1500 mg.

mEq = 1500 mg *1 / 74.5 mg = 20.13 mEq.

A patient is to receive 2 mEq of sodium chloride per kilogram of body weight. If the person weighs 132 lb, how many milliliters of a 0.9% NaCl (MW = 59) solution should be administered?

• 393 mL

• 7877 mL

• 787 mL

• 1550 mL

How many milliequivalents of Na+ would be contained in a 30-ml dose of the following solution? 

Disodium hydrogen phosphate 55 g

Purified water up to 100 ml

MW of  disodium hydrogen phosphate (Na²HPO₄ . 7H20) is 268.

• 100

• 150

• 123

• 200

What is the percent concentration of a solution containing 8 mEq of magnesium sulfate

(MgSO4.7H2O, MW 247) per liter?

• 1.096%

• 0.150%

• 0.099%

• 0.110%