关于溶液稀释问题遵循的基本原则就是mole doesn't change at all。
Water is then added to achieve the molarity desired for a particular solution. This process is called dilution. For example, the common acids are purchased as concentrated solutions and diluted as needed. A typical dilution calculation involves determining how much water must be added to an amount of stock solution to achieve a solution of the desired concentration. The key to doing these calculations is to remember that
Moles of solute after dilution moles of solute before dilution
(a) A measuring pipet is used to transfer 28.7 ml of 17.4 M acetic acid solution to a volumetric flask.
(b) Water is added to the flask to the calibration mark.
(c) The resulting solution is 1.00 M acetic acid.