Chemistry: Stock Solutions and Concentration Calculations

Study Notes

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)

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

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).

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.

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).

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.