Final answer:
The relationship between mMol/L and meq/L is that for monovalent ions, the values are equivalent, while for divalent ions, the mMol/L value must be multiplied by the ion's charge to convert to meq/L. This is because milliequivalents consider both the ion concentration and the charge of ions in a solution.
Step-by-step explanation:
The relationship between millimoles per liter (mMol/L) and milliequivalents per liter (meq/L) depends on the charge of the ions in solution. In chemistry, molarity refers to the number of moles of solute per liter of solution, and when dealing with very dilute solutions or small quantities, concentrations are often expressed in millimoles (mMol).
The unit milliequivalent takes into account both the concentration of ions in millimoles and their respective charges in a solution. For ions with a charge of one, one milliequivalent is equal to one millimole. However, for ions with a charge of two, such as calcium, one milliequivalent is half of a millimole.
Osmotic pressure calculations in biological systems frequently use milliequivalents, especially when discussing electrolyte concentrations in body fluids. To convert mMol/L to meq/L for a monovalent ion (like Na+ or K+), the values are equivalent.
For divalent ions (like Ca2+ or Mg2+), one must multiply the mMol/L concentration by the valence (charge) of the ion to convert to meq/L. Hence, for sodium (Na+), 1 mMol/L is also 1 meq/L, but for calcium (Ca2+), 1 mMol/L is 2 meq/L because of the 2+ charge.