Here are the essential concepts you must grasp in order to answer the question correctly.
Milliequivalents (mEq)
Milliequivalents (mEq) is a unit of measurement used to express the concentration of ions in a solution. It accounts for the charge of the ion, allowing for a standardized way to compare different ions. For magnesium (Mg²⁺), 1 mEq corresponds to 1 millimole of the ion, considering its divalent charge.
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Concentration Calculation
Concentration refers to the amount of a substance in a given volume of solution. In this case, the concentration of Mg²⁺ is given as 3 mEq/L, which means there are 3 milliequivalents of magnesium per liter of blood. To find the total amount in a different volume, such as 250 mL, one must convert the volume to liters and apply the concentration.
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Conversion from mEq to mg
To convert milliequivalents (mEq) of an ion to milligrams (mg), one must use the molecular weight of the ion. For magnesium, the atomic weight is approximately 24.3 g/mol. Since 1 mEq of Mg²⁺ equals 12.15 mg (24.3 g/mol divided by 2), this conversion is essential for determining the mass of magnesium in the specified volume of blood.
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