require 400 mL of a 0.4 M NaOH solution and you have a 1.2 M stock solution. How would you make up the solution?
To make 400 mL of a 0.4 M NaOH solution from a 1.2 M stock solution, you will need to dilute the stock solution by adding a certain volume of water. Here's how you can calculate the exact amount of stock solution and water required:
1. Use the dilution formula: C1V1 = C2V2
Where:
- C1 is the initial concentration (1.2 M) of the stock solution
- V1 is the volume (unknown) of the stock solution you need to measure
- C2 is the final concentration (0.4 M) of the diluted solution
- V2 is the final volume (400 mL) of the diluted solution you want to prepare
2. Substitute the known values into the formula:
(1.2 M) * V1 = (0.4 M) * (400 mL)
3. Rearrange the formula to solve for V1:
V1 = (0.4 M) * (400 mL) / (1.2 M)
V1 = (0.4 * 400) / 1.2
V1 = 400 / 3
V1 ≈ 133.33 mL
So, you need to measure approximately 133.33 mL of the 1.2 M NaOH stock solution.
4. To make up the final volume of 400 mL, subtract V1 from 400 mL:
Final volume of water = 400 mL - 133.33 mL
Final volume of water ≈ 266.67 mL
Therefore, you will need to add approximately 266.67 mL of water to the measured 133.33 mL of the 1.2 M NaOH stock solution to make 400 mL of a 0.4 M NaOH solution.