This document provides explanations and examples of different units used to measure concentrations in solutions: mg/L, mmol/L, mEq/L, and mOsm/L. It explains that mg/L can be converted to mmol/L by dividing the concentration in mg/L by the molecular weight. The number of mmol/L can then be multiplied by the charge of the ion to get mEq/L, or multiplied by the number of ions to get mOsm/L. An example is provided to demonstrate converting a calcium concentration of 10 mg/dl (100 mg/L) to mmol/L, mEq/L, and mOsm/L. The summary reiterates the steps to convert