Chemistry: Stock Solutions and Concentration Calculations

Stock Solutions

• A stock solution is a concentrated solution of a known solute, used to prepare multiple diluted solutions
• Stock solutions are typically prepared at a high concentration to minimize storage volume and facilitate convenient dilution
• Common stock solution concentrations:
  • 1M (1 mole/L)
  • 0.1M (0.1 moles/L)
  • 10% (10 grams/100 mL)

Concentration Calculations

• Molarity (M) Calculations
  • Molarity (M) = moles of solute / liters of solution
  • M1V1 = M2V2 (dilution formula, where M1 and V1 are initial concentration and volume, and M2 and V2 are final concentration and volume)
• Dilution Calculations
  • To dilute a solution:
    • Calculate the volume of stock solution needed: V1 = (M2V2) / M1
    • Add the calculated volume of stock solution to enough solvent to make the desired final volume (V2)
• Example Problems
  • If you have a 2M stock solution of NaCl and want to make 100 mL of a 0.5M solution, how much stock solution do you need?
    • V1 = (0.5M × 100 mL) / 2M = 25 mL of stock solution
  • If you want to dilute 10 mL of a 5M stock solution to 50 mL, what will be the final concentration?
    • M2 = M1 × (V1 / V2) = 5M × (10 mL / 50 mL) = 1M

Stock Solutions

• A stock solution is a concentrated solution of a known solute, used to prepare multiple diluted solutions.
• Stock solutions are prepared at a high concentration to minimize storage volume and facilitate convenient dilution.
• Common stock solution concentrations include 1M (1 mole/L), 0.1M (0.1 moles/L), and 10% (10 grams/100 mL).

Concentration Calculations

Molarity (M) Calculations

• Molarity (M) is calculated by dividing the number of moles of solute by the number of liters of solution.
• The dilution formula is M1V1 = M2V2, where M1 and V1 are initial concentration and volume, and M2 and V2 are final concentration and volume.

Dilution Calculations

• To dilute a solution, calculate the volume of stock solution needed using the formula V1 = (M2V2) / M1.
• Add the calculated volume of stock solution to enough solvent to make the desired final volume (V2).

Example Problems

• To make 100 mL of a 0.5M solution from a 2M stock solution of NaCl, 25 mL of stock solution are needed.
• If 10 mL of a 5M stock solution are diluted to 50 mL, the final concentration will be 1M.