describe the preparation of : 250ml of 0.1N (Na2Co3) from the solid reagent.
The equivalent weight of Na2CO3 is 53. For 0.1 N solutionof Na2CO3 we need 0.1*53 = 5.3 g of Na2CO3 for 1 L. For 0.25 L of solution we need 0.25*5.3 = 1.325 g of Na2CO3.
Thus, we should weigh 1.325 g of Na2CO3 and transfer it into the 250 mL volumetric flask and add water to below the neck portion of the flask to dissolve the solid. If you shake the flask to help dissolve the solid, make sure the stopper is in place. After the solid is completely dissolved, very carefully fill the flask to the mark.