The concentration of Cl^- ion in blood is approximately 100 mEq/L. How many milliliters of blood would be needed to obtain 1.0 g of Cl^- ions?

Verified step by step guidance

1. Step 1: Understand the given information. The concentration of Cl⁻ ions is 100 mEq/L, and we need to determine the volume of blood (in milliliters) required to obtain 1.0 g of Cl⁻ ions.
2. Step 2: Convert the mass of Cl⁻ ions (1.0 g) into moles. Use the molar mass of Cl⁻, which is approximately 35.45 g/mol. The formula to use is: \( \text{moles of Cl⁻} = \frac{\text{mass of Cl⁻}}{\text{molar mass of Cl⁻}} \).
3. Step 3: Convert the moles of Cl⁻ into milliequivalents (mEq). Since Cl⁻ is a monovalent ion, 1 mole of Cl⁻ is equivalent to 1 equivalent, and 1 equivalent is equal to 1000 milliequivalents. Use the formula: \( \text{mEq of Cl⁻} = \text{moles of Cl⁻} \times 1000 \).
4. Step 4: Use the concentration of Cl⁻ ions in blood (100 mEq/L) to calculate the volume of blood required. Rearrange the formula for concentration: \( \text{Volume (L)} = \frac{\text{mEq of Cl⁻}}{\text{Concentration (mEq/L)}} \).
5. Step 5: Convert the volume from liters to milliliters. Since 1 L = 1000 mL, multiply the volume in liters by 1000 to get the volume in milliliters.

Key Concepts

Molarity and Equivalent Weight

Molarity is a measure of concentration expressed as moles of solute per liter of solution. For ions like Cl⁻, the equivalent weight is the mass of the ion that combines with or displaces one mole of hydrogen ions. Understanding these concepts is crucial for converting between mass and concentration in solutions.

Conversion between Mass and Moles

To find the number of moles from a given mass, the formula used is: moles = mass (g) / molar mass (g/mol). For Cl⁻, the molar mass is approximately 35.45 g/mol. This conversion is essential for determining how many moles of Cl⁻ correspond to 1.0 g, which will then be used to find the volume of blood needed.

Volume Calculation from Concentration

Once the number of moles of Cl⁻ is determined, the volume of blood required can be calculated using the concentration of Cl⁻ in blood. The formula is: volume (L) = moles / concentration (mEq/L). This step is vital for translating the amount of Cl⁻ needed into a practical volume of blood.