计算化学溶液的浓度是所有化学学生必须在他们的研究早期发展的基本技能。什么是注意力?浓度是指溶解在溶剂中的溶质的量。我们通常认为溶质是添加到溶剂中的固体(例如,将食盐添加到水中),但溶质可以很容易地存在于另一相中。例如,如果我们向水中加入少量乙醇,则乙醇是溶质,水是溶剂。如果我们在较大量的乙醇中加入少量水,那么水可能是溶质!一旦确定溶液中的溶质和溶剂,就可以确定其浓度。浓度可以用几种不同的方式表示,使用质量百分比组成,体积百分比,摩尔分数,摩尔浓度,摩尔浓度或当量浓度。在制备液体溶液时最常使用的体积百分比或体积/体积百分比。体积百分比定义为:v / v%= [(溶质体积)/(溶液体积)]×100%注意体积百分比是相对于溶液体积而不是溶剂体积。例如,葡萄酒约为12%v / v乙醇。这意味着每100毫升葡萄酒中含有12毫升乙醇。重要的是要实现液体和气体体积不一定是添加剂。如果你混合12毫升乙醇和100毫升葡萄酒,你会得到少于112毫升的溶液。作为另一个例子,可以通过取700ml异丙醇并加入足够的水以获得1000ml溶液(其不是300ml)来制备70%v / v摩擦醇。

英国基尔大学化学Assignment代写:单位和稀释

Calculating the concentration of a chemical solution is a basic skill all students of chemistry must develop early in their studies. What is concentration? Concentration refers to the amount of solute that is dissolved in a solvent. We normally think of a solute as a solid that is added to a solvent (e.g., adding table salt to water), but the solute could just as easily exist in another phase. For example, if we add a small amount of ethanol to water, then the ethanol is the solute and the water is the solvent. If we add a smaller amount of water to a larger amount of ethanol, then the water could be the solute! Once you have identified the solute and solvent in a solution, you are ready to determine its concentration. Concentration may be expressed several different ways, using percent composition by mass, volume percent, mole fraction, molarity, molality, or normality. Volume percent or volume/volume percent most often is used when preparing solutions of liquids. Volume percent is defined as: v/v % = [(volume of solute)/(volume of solution)] x 100% Note that volume percent is relative to the volume of solution, not the volume of solvent. For example, wine is about 12% v/v ethanol. This means there is 12 ml ethanol for every 100 ml of wine. It is important to realize liquid and gas volumes are not necessarily additive. If you mix 12 ml of ethanol and 100 ml of wine, you will get less than 112 ml of solution. As another example, 70% v/v rubbing alcohol may be prepared by taking 700 ml of isopropyl alcohol and adding sufficient water to obtain 1000 ml of solution (which will not be 300 ml).

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