For the easy reference,you prepare a concentrated stock solution and you dilute it according to your requirement by the below given procedure.You prepare a solution by dissolving a known mass of solute (often a solid) into a specific amount of a solvent. One of the most common ways to express the concentration of the solution is M or molarity, which is moles of solute per liter of solution.
Prepare 1 liter of 1.00 M NaCl solution.
First calculate the molar mass of NaCl which is the mass of a mole of Na plus the mass of a mole of Cl or 22.99 + 35.45 = 58.44 g/mol
1) Weigh out 58.44 g NaCl.
2) Place the NaCl in a 1 liter volumetric flask.
3) Add a small volume of distilled, deionized water to dissolve the salt.
4) Fill the flask to the 1 L line.
If a different molarity is required, then multiply that number times the molar mass of NaCl. For example, if you wanted a 0.5 M solution, you would use 0.5 x 58.44 g/mol of NaCl in 1 L of solution or 29.22 g of NaCl.
once your stock solution is prepared you can dilute it to a particular volume to make a new, more dilute solution. The key equation here is
M1V1 = M2V2
Remember that number of moles you are working with is constant whether in the stock solution or in the more dilute new solution. Since molarity times volume equals moles, that it what the equation above is talking about. M1V1 is the molarity (moles per liter) times the volume of the stock solution and M2V2 is the molarity times the volume of the new solution. So you are usually given three of the variables in the problem and you simply plug them in and solve for the missing fourth variable.
In terms of actual laboratory practice to make a new solution from a stock solution, first you calculate how many milliliters of the stock solution that you need to make the new solution. Then measure out the required number of mL's of the stock solution in a graduated cylinder and pour into into a new flask. Then add fresh water (or whatever solvent you are working with) to the flask until the level reaches the required number of mL's of the new solution. Then stir the solution to mix evenly. Now you have a new, more dilute solution of a know concentration.