A patient is prescribed potassium chloride (KCl) 20 mEq orally twice daily. You have KCl 10% solution (1.34 mEq/mL) available. How many milliliters should the patient take per dose?

Question: A patient is prescribed potassium chloride (KCl) 20 mEq orally twice daily. You have KCl 10% solution (1.34 mEq/mL) available. How many milliliters should the patient take per dose?

Answer options:

• 7.5 mL
• 10.0 mL
• 12.5 mL ✅ 15.0 mL

Correct answer: 15.0 mL

Explanation: First, understand that KCl 10% solution means 10g of KCl per 100mL of solution. The molecular weight of KCl is approximately 74.5 g/mol, which means 1 gram of KCl is approximately 13.4 mEq. Therefore, 10g of KCl is 134 mEq. So, 10% KCl solution has 134 mEq in 100 mL, or 1.34 mEq/mL. If the patient needs 20 mEq per dose, they require 20 mEq / 1.34 mEq/mL ≈ 14.93 mL per dose, which rounds to 15.0 mL.