The molarity of a solution is moles of solute per liter of solution. You need to calculate how many moles of solute are needed for given molarity and volume, then calculate the mass of the required amount of moles.
1. Find moles:
2.50L x 1.34 moles/1 L = 3.35 moles of NaCl
molar mass of NaCl = 22.99 g/mol + 35.45 g/mole = 58.45 g/mol
3.35 moles NaCl x 58.45 g/mol = 196 grams NaCl
Steps to prepare this soluton:
1. Weigh out 196 grams of NaCl.
2. Pour NaCl into 250 ml volumetric flask.
3. Add deionized or distilled water to just below the mark painted on the neck of the flask.
4. Cap or stopper the flask, invert and mix by swirling until the sodium chloride is dissolved.
5. Using a dropper if necessary, add enough additional water so that the meniscus (lowest part of the water line) is at the painted on line of the neck of the flask.
6. Invert and swirl again.