How do we prepare 500mL of 0.5 percent w/v solution of NaOH if we have stock solution of 50 percent w/v NaOH on hand?

c1v1 = c2v2

50*?mL = 0.5 x 500 mL
Solve for ?mL. Add ?ml stock to a 500 mL volumetric flask and make to the mark.

To prepare a 500 mL solution of 0.5% w/v NaOH from a stock solution of 50% w/v NaOH, you need to dilute the stock solution with the appropriate amount of water. Here's how you can calculate the required volumes:

Step 1: Determine the amount of NaOH needed:
- The desired concentration is 0.5% w/v, which means 0.5 grams of NaOH per 100 mL of solution.
- Since you want to prepare a 500 mL solution, you'll need (0.5 grams/100 mL) * 500 mL = 2.5 grams of NaOH.

Step 2: Calculate the volume of the stock solution required:
- The stock solution is 50% w/v NaOH, meaning it contains 50 grams of NaOH per 100 mL.
- To find out how much stock solution you need, set up the following equation:
(50 grams/100 mL) * X mL = 2.5 grams
- Solving for X (the volume of stock solution required):
X = (2.5 grams * 100 mL) / 50 grams
X = 5 mL

So, to prepare a 500 mL solution of 0.5% w/v NaOH, you will need to measure 5 mL of the 50% w/v NaOH stock solution. Then, add water to reach a total volume of 500 mL.