The biochemist needs 250 mL of a 0.4 M NaCl solution. She has a stock solution of 2 M. How many mL of the stock solution should she use?
["How a Biochemist Prepares 250 mL of 0.4 M NaCl Using a 2 M Stock Solution: A Clear Step-by-Step Guide", "Creating accurate cannabis extractions or conducting essential biochemistry experiments often requires precise preparation of saline solutions. For many lab tasks, a common challenge is diluting a concentrated stock solution to achieve the desired molarity. This SEO-optimized guide explains how a biochemist can prepare 250 mL of 0.4 M NaCl solution using a 2 M stock solution, highlighting key principles of dilution calculations for reliable, reproducible results.", "### Why Accurate Dilution Matters in Biochemistry", "In biochemistry and organic chemistry, precise molarity is critical. Incorrect concentrations can skew reaction yields, compromise sample integrity, or invalidate experimental data. Proper dilution techniques ensure consistency and scalability—whether scaling up or down in a lab setting.", "### The Chemistry Behind the Dilution", "The chemistry follows the dilution formula:", "[\nC_1 V_1 = C_2 V_2\n]", "Where:\n- ( C_1 ) = concentration of stock solution = 2.0 M\n- ( V_1 ) = volume of stock solution needed (unknown)\n- ( C_2 ) = desired concentration = 0.4 M\n- ( V_2 ) = final volume = 250 mL = 0.250 L", "### Step-by-Step Calculation", "1. Convert volumes to liters (optional but recommended for precision):\n ( V_2 = 250 , \ ext{mL} = 0.250 , \ ext{L} )\n ( C_1 = 2.0 , \ ext{M}, \quad C_2 = 0.4 , \ ext{M} )", "2. Plug values into the dilution equation:\n [\n (2.0 , \ ext{M}) \ imes V_1 = (0.4 , \ ext{M}) \ imes (0.250 , \ ext{L})\n ]", "3. Solve for ( V_1 ):\n [\n V_1 = \frac{(0.4 \ imes 0.250)}{2.0} = \frac{0.100}{2.0} = 0.050 , \ ext{L} = 50 , \ ext{mL}\n ]", "### Answer:", "The biochemist needs to use 50 mL of the 2 M NaCl stock solution to prepare 250 mL of a 0.4 M NaCl solution.", "### Practical Tips for Lab Accuracy", "- Use calibrated pipettes: Ensure measurement precision with volume flasks and graduated pipettes.\n- Measure cold solutions carefully: NaCl solution volume can vary slightly with temperature—measure at room temperature.\n- Mix thoroughly: After adding the stock solution to distilled water, invert and swirl gently to ensure a homogeneous, consistent solution.\n- Document everything: Record concentrations, volumes, and preparation date for safety and reproducibility.", "### Conclusion", "Diluting concentrated NaCl stock to achieve precise molarities—like preparing 0.4 M NaCl in 250 mL—is straightforward with the dilution formula ( C_1 V_1 = C_2 V_2 ). By using exactly 50 mL of a 2 M stock solution, the biochemist ensures accuracy vital for reliable experimental outcomes. Mastering such calculations empowers scientists to streamline workflows and maintain high standards in biochem and lab research.", "---", "Keywords: NaCl dilution, 0.4 M NaCl, 2 M stock solution, biochemistry lab, dilution calculation, biochemist procedure, lab preparation, Molarity dilution formula, accurate saline preparation, preparing NaCl solution."]
