How do you prepare 250ml 15m solution of naco3 in a volumetric flask do presume a solvent ie h20 but then you have to presume volumes and conc and because 15M wanted you cant use the flask to dilute?

Answer 1

Did you mean 250 mL of 0.15 M Na2CO3? (It's impossible to make a 15 M Na2CO3 solution, as Na2CO3 is not that soluble.) Yes, you can assume that this will be an aqueous solution.

Steps.

1. Calculate the mass of solid Na2CO3 needed.

2. Place this mass of Na2CO3 in the volumetric flask.

3. Add some water and swirl to dissolve the Na2CO3.

4. Carefully add more water until the total volume of solution is 250 mL, as indicated by the line etched on the neck of the volumetric flask.

250 mL x 1 L x 0.15 mol Na2CO3 x 105.99 g Na2CO3 = 4.0 g Na2CO3 needed

........... 1000 mL ......... 1 L ..................1 mol Na2CO3

Answer 2

To prepare a 250ml 15M NaCO3 solution in a volumetric flask without using the flask to dilute, you would first calculate the mass of NaCO3 needed based on its molar mass. Then, dissolve this mass in a small volume of water in a separate container and transfer it quantitatively to the 250ml volumetric flask, and then add enough water to make up to the mark. Finally, mix thoroughly to ensure homogeneous distribution.