溶液和溶解度
Chapter 3 solutions and solubility
溶液和溶解度
3.1 Types of Solutions 溶液的类型
Ⅰ.Key terms 关键词
Solution 溶液
Solvent 溶剂
Solutes 溶质
Concentrated solution 浓溶液
Diluted solution 稀溶液
Aqueous solution 水溶液
Miscible 相溶
Immiscible 不相溶
Alloys 合金
Saturated solution 饱和溶液
Unsaturated solution 不饱和溶液
II.Topics 知识点
·What is solution?
A homogeneous mixture of a solvent and one or more solutes. 溶液是由一种溶剂和一种或多种溶质组成的混合物。·What is solvent?
A substance that has other substances dissolved in it.
溶剂是其它物质能够溶解在其中的物质。
·What is solute?
A substance that is dissolved in a solution.
溶质是溶解在溶液中的物质。
·What is concentrated solution?
A solution that has a higher proportion of solute to solvent than a dilute solution.
浓溶液是溶质与溶剂比例比稀溶液高的溶液。
·What is dilute solution?
It has a lower proportion of solute to solvent than a concentrated solution.
稀溶液是溶质与溶剂比例比浓溶液低的溶液。
·A solution can be a gas, a liquid, or a solid.
·An aqueous solution is a solution in which water is the solvent.
水溶液是指水作为溶剂的溶液。
·What is miscible?
A term used to describe substances that are able to combine with each other in any proportion
用来描述物质能够互相以任意比例溶合的词汇。
·What is immiscible?
A term used to describe substances that are not able to combine with each other in a solution.
用来描述物质不能够彼此溶合的词汇。
·What is alloys?
solid solutions of metals are called alloys.
金属形成的固体溶液叫做合金。
·What is solubility?
the mass of solute that dissolves in a given quanity of solvent at a specific temperature.
在一定的温度下，溶于固定量溶剂中的溶质的质量。
·What is saturated solution?
A solution in which no more of a particular solute can be dissolved at a specific temperature.
在一定温度下，不能再溶解特定溶质的溶液。
·What is unsaturated solution?
A solution in which more of a particular solute can be
dissolved at a specific temperature.
在一定温度下，能够再溶解特定溶质的溶液。
Ⅲ.Practices
1.Give examples of each type of solution.
(a) solid solution
(b) liquid solution
(c) gaseous solution (at room temperature)
2.Explain the term “homogeneous mixture.”
3.Imagine you are given a filtered solution of sodium chloride. How can you decide whether the solution is saturated or unsaturated?
4.Distinguish between the following terms: soluble, miscible, and immiscible.
5.You are given three liquids. One is a pure substance, and the second is a solution of two miscible liquids. The third is a solution composed of a solid solute dissolved in a liquid solvent. Describe the procedure you would follow to distinguish among the three solutions.
6.What type of solute dissolves in a polar solvent, such as water? Give an example.
3.2 Factors That Affect Rate of Dissolving and Solubility 影响溶解速率和溶解度的因素
Ⅰ.Key terms 关键词
rate of dissolving 溶解速率
dipole 偶极
dipole-dipole attraction 偶极间作用力
hydrogen bonding 氢键
ion-dipole attractions 离子偶极间作用力
hydrated 水合的
electrolyte 电解质
non-electrolytes 非电解质
Ⅱ.Topics 知识点
·What is rate of dissolving?
The speed at which a solute dissolves in a solvent.
溶质溶解在溶剂中的速率。
·Factors That Affect the Rate of Dissolving
a.for most solid solutes, the rate of dissolving is greater
at higher temperatures.
对于大多数的固体溶质，温度越高溶解速率越大。
b.Agitating a mixture by stirring or by shaking the container increases the rate of dissolving.
通过搅拌混合物或者摇动容器来增加溶解速率。
c.Decreasing the size of the particles increases the rate of dissolving.
减小微粒来增加溶解速率。
·The Process of Dissolving at the Molecular Level
Step 1 The forces between the particles in the solid must be broken.This step always requires energy. In an ionic solid, the forces that are holding the ions together must be broken. In a molecular solid, the forces between the molecules must be broken.
固体微粒间的作用力被打破。这个步骤一定需要能量。在离子固体中，使离子结合的作用力必须被打破。在分子固体中，分子间的作用力必须被打破。
Step 2 Some of the intermolecular forces between the particles in theliquid must be broken. This step also requires energy. 一些液体分子间的作用力必须被打破。这个步骤也是需要能量的。Step 3There is an attraction between the particles of the solid and the particles of the liquid. This step always gives off energy.
固体微粒和液体微粒间形成作用力。这个步骤一定是放出能量的。·The solubility about Polar and Non-Polar Substances
Like dissolve in like
相似相溶
·What is dipole ?
A dipole consists of two opposite charges that are separated by a short distance.
偶极包括了两个相距一段很短距离的相反价极。
·Solubility and Intermolecular Forces
The attraction between the opposite charges on two different polar molecules is called a dipole-dipole attraction.
在两个极性分子的相反价极间存在的作用力叫做偶极间作用力。Dipole-dipole attractions are intermolecular—they act between molecules. Usually they are only about 1% as strong as an ionic or covalent bond.
偶极间作用力是分子间力——它们存在于分子之间。通常它们的强度只有离子键或共价键的1%。
·What is hydrogen bonding?
It occurs between the oxygen atom or nitrogen atom on one molecule and the hydrogen atoms on a nearby molecule.
氢键存在于一个分子中的氧原子或者氮原子和相近的另一个分子中的氢原子之间。
Hydrogen bonding is much stronger than an ordinary dipole-dipole attraction. It is much weaker, however, than the covalent bond between the oxygen or nitrogen and hydrogen atoms in a molecule.
氢键比普通的偶极间作用力强的多。但是比一般分子内氢原子和氧原子或者氮原子间的共价键弱的多。
·What is Ion-Dipole Attractions？
Attractive forces between an ion and a polar molecule.
离子和极性分子间的作用力叫做离子-偶极间作用力。
If ion-dipole attractions can replace the ionic bonds between the cations and anions in an ionic compound, the compound will dissolve. Generally an ionic compound will dissolve in a polar solvent.
如果离子偶极间作用作用力能够代替离子化合物中阴阳离子间的离子键，那么这个化合物会溶解。一般情况下离子化合物溶于极性溶剂。When ions are present in an aqueous solution, each ion is hydrated. This means that it is surrounded by water molecules. 当离子在水溶液中存在时，每一个离子都是水合状态。这意味着它周围都被水离子环绕。
Hydrated ions can move through a solution and conduct electricity.
水合离子能够在溶液中移动并导电。
·What is electrolyte?
A solute that forms an aqueous solution with the ability to
conduct electricity is called an electrolyte.
在水溶液中能够导电的溶质叫做电解质。
·An Exception: Insoluble Ionic Compounds
Although most ionic compounds are soluble in water, some are not very soluble at all. The attraction between ions is difficult to break. As a result, compounds with very strong ionic bonds, such as silver chloride, tend to be less soluble in water than compounds with weak ionic bonds, such as sodium chloride.
虽然大多数的离子化合物溶于水，但也有一些根本不溶。离子内的作用力很难打破。因此，有强离子键的化合物，例如氯化银在水中的溶解度比那些拥有弱离子键的化合物，例如氯化钠，小得多。·Using Electronegativity Differences to Predict Solubility
You can predict the solubility of a binary compound.If there is a large difference in the two electronegativities, the bond between the elements is polar or even ionic. This type of compound probably dissolves in water.
（利用电负性的差别）你可以预测二元化合物的溶解度。如果两种（原子）电负性差别非常大，那么它们之间的键就是极性键甚至是离子键。这种化合物就可能溶解在水中。
If there is only a small difference in the two
electronegativities, the bond is not polar or ionic. This type of compound probably does not dissolve in water.
如果两种（原子）电负性差别比较小，那么它们之间的键就是非极性键或者离子键。这种类型的化合物可能不溶于水。
·The Solubility of Covalent Compounds
Many covalent compounds do not have negative and positive charges to attract water molecules. Thus they are not soluble in water.
许多共价化合物没有正价极和负价极来吸引水分子。因此它们不溶于水。
There are some exceptions, however. Methanol (a component of windshield washer fluid), ethanol (the “alcohol” in alcoholic beverages), and sugars (such as sucrose) are examples of covalent compounds that are extremely soluble in water. These compounds dissolve because their molecules contain polar bonds, which are able to form hydrogen bonds with water.
当然，也有一些例外。甲醇（汽车挡风玻璃水的一种成分），乙醇（酒精饮料中的“酒精”）和糖（例如蔗糖）就是共价化合物极易溶于水的例子。这些化合物因为它们的分子中包含极性键，能够与水形成氢键。
For example, sucrose molecules have a number of sites that can form a hydrogen bond with water to replace the attraction
between the sucrose molecules.
例如，蔗糖分子中有些位置可以与水形成氢键来代替原先的蔗糖分子间的吸引力。
The sucrose molecules separate and become hydrated, just like dissolved ions.The molecules remain neutral, however.
蔗糖分子彼此分离变成了水合物，就像溶于水的离子。然而，分子依然保持中性。
sucrose and other soluble covalent compounds do not conduct electricity when dissolved in water. They are non-electrolytes 蔗糖和其它溶于水的共价化合物溶于水时不能导电。它们是非电解质·Insoluble Covalent Compounds
In general, ionic solutes and polar covalent solutes both dissolve in polar solvents. Non-polar solutes dissolve in non-polar solvents. The phrase like dissolves like summarizes
these observations. It means that solutes and solvents that have similar properties form solutions.If a compound has both polar and non-polar components, it may dissolve in both polar and non-polar solvents.
通常，离子溶质和极性共价溶质都能溶解在极性溶剂中。非极性溶质溶解在非极性溶剂中。这种现象叫做“相似相溶”。它的意思是形成溶液的溶质和溶剂有相似的性质。如果一种化合物同时具有极性和非极性成分，它就既可以溶解在极性溶剂又可以溶解在非极性溶剂中。·Factors That Affect Solubility
a.Molecule Size and Solubility
Small molecules are often more soluble than larger molecules. 小分子通常比大分子易溶。
b.Temperature and Solubility
When a solid dissolves in a liquid, energy is needed to break the strong bonds between particles in the solid. At higher temperatures, more energy is present. Thus, the solubility of most solids increases with temperature.
当固体溶于液体时，能量被用于打破固体微粒之间的强烈化学键。更高的温度显示更多的能量。因此，固体的溶解度随温度的升高而增加。
The bonds between particles in a liquid are not as strong as the bonds between particles in a solid. When a liquid dissolves in a liquid, additional energy is not needed. Thus, the solubility of most liquids is not greatly affected by temperature.
液体微粒间的作用力不像固体微粒那么大。当液体溶于液体时，不需要额外的能量。因此，大多数液体的溶解度被温度影响的不大。
Gas particles move quickly and have a great deal of kinetic energy. When a gas dissolves in a liquid, it loses some of this energy. At higher temperatures, the dissolved gas gains energy again. As a result, the gas comes out of solution and is less soluble. Thus, the solubility of gases decreases with higher temperatures.
气体微粒移动的很快并具有大量的动能。当气体溶解在液体中时，它就丢失了一些能量。在高温时，气体又重新获得了能量。结果，气体又从溶液中逸出，导致溶解度下降。因此，气体的溶解度随温度的升高而降低。
This property of gases makes heat pollution a serious problem. Many industries and power plants use water to cool down overheated machinery.The resulting hot water is then returned to local rivers or lakes.Adding warm water into a river or lake does not seem like actual pollution. The heat from the water,
however, increases the temperature of the body of water. As the temperature increases, the dissolved oxygen in the water decreases. Fish and other aquatic wildlife and plants may not have enough oxygen to breathe.
气体的这种性质造成了热污染的一系列问题。许多工厂和大型企业用水来降低过热的机器。这导致了热水流入到河流或者湖泊中。河流湖泊中加入热水看起来没什么真正的污染。但是，来自水的热增加了水体的温度。随着温度的增加，水中溶解的氧气量降低。鱼和其它的野生水生物和植物就没有足够的氧气来呼吸。
c.Pressure and Solubility
Changes in pressure have hardly any effect on solid and liquid solutions. Such changes do affect the solubility of a gas in a liquid solvent, however. The solubility of the gas is directly proportional to the pressure of the gas above the liquid. For example, the solubility of oxygen in lake water depends on the air pressure above the lake.
改变压强很难对固体和液体有什么影响。但是这种改变确实影响了气体在液体中的溶解度。气体的溶解度直接跟液体上的压强成比例。例如，湖水中氧气的溶解度依赖于湖面上的压强。
Ⅲ.Practices 练习
1.When water vaporizes, which type of attraction,
intramolecular or intermolecular, is broken? Explain.
2.Describe the effect of increasing temperature on the
solubility of (a) a typical solid in water (b) a gas in water 3.Sugar is more soluble in water than salt. Why does a salt
solution (brine) conduct electricity, while a sugar solution does not?
4.The graph shows the solubility of various substances plotted against the temperature of the solution.
(a) Which substance decreases in solubility as the temperature increases?
(b) Which substance is least soluble at room temperature? Which substance is most soluble at room temperature?
(c) The solubility of which substance is least affected by a change in temperature?
(d) At what temperature is the solubility of potassium chlorate equal to 40 g/100 g of water?
(e) 20 mL of a saturated solution of potassium nitrate at 50?C is cooled to 20?C. Approximately what mass of solid will precipitate from the solution? Why is it not possible to use the graph to interpolate an accurate value？
3.3The Concentration of Solutions 溶液的浓度Ⅰ.Key terms 关键词
Concentration 浓度
mass/volume percent 质量/体积百分比
mass/mass percent 质量/质量百分比
volume/volume percent体积/体积百分比
parts per million (ppm)百万分率
parts per billion (ppb)十亿分率
Molar concentration(molarity)摩尔浓度
II.Topics 知识点
·What is the concentration?
the amount of solute per quantity of solvent.
定量溶剂中所溶解的溶质量。
·A mass/volume percent gives the mass of solute dissolved in a volume of solution, expressed as a percent. The mass/volume percent is also referred to as the percent (m/v).
质量/体积百分比给出了在一体积溶剂中溶解的溶质质量，表达为百分比。质量/体积百分比也被标记为（m/v）。
Mass/volume percent =×100%
Notice that the number of grams of solute per 100 mL of solution is numerically equal to the mass/volume percent.
注意每100毫升溶液中溶解的溶质的克数在数值上等于质量/体积百分比。
·A mass/mass percent gives the mass of a solute divided by the mass of solution, expressed as a percent. The mass/mass percent is also referred to as the percent (m/m), or the mass percent. 质量/质量百分比给出了溶质质量除以溶液质量百分比的表达式。质量/质量百分比也可以标记为(m/m)或质量百分比。
Mass/mass percent =× 100%
Notice that the number of grams of solute per 100 g of solution is numerically equal to the mass/mass percent.
注意每100g溶液中溶解的溶质的克数在数值上等于质量/质量百分比。
·A volume/volume percent gives the volume of solute divided by the volume of solution, expressed as a percent.The volume/volume percent is also referred to as the volume percent concentration, volume percent, percent (v/v), or the percent by volume.
体积/体积百分比给出了溶质体积除以溶液体积的百分比表达式。体积/体积百分比作为体积百分比浓度也被标记为(v/v)，或体积百分比。Volume/volume percent =× 100%
·The concentration of a very small quantity of a substance in the human body, or in the environment, can be expressed in parts per million (ppm) and parts per billion (ppb). Both parts per million and parts per billion are usually mass/mass relationships.
在人体中或者环境里很小量的物质的浓度能够被百万分率（ppm）和十亿分率（ppb）表示。百万分率和十亿分率都是表示质量/质量的关系。
ppm =× 106 or
ppb =× 109 or
·What is the molar concentration?
Molar concentration is the number of moles of solute in 1 L of solution. Notice that the volume of the solution in litres is used, rather than the volume of the solvent in millilitres.
Molar concentration is also known as molarity.
摩尔浓度是指一升溶液中所溶解的溶质的摩尔数。注意溶液的体积单位通常为“升”而不是“毫升”。摩尔浓度也可写作“molarity”。
This formula can be shortened to give
Ⅲ.Practices
1.Ammonium chloride, NH4Cl, is a very soluble salt. 300 g of ammonium chloride are dissolved in 600 mL of water. What is the percent (m/m) of the solution?
2.A researcher measures 85.1 mL of a solution of liquid hydrocarbons.The researcher then distills the sample to separate the pure liquids.If 20.3 mL of the hydrocarbon hexane are recovered, what is its percent(v/v) in the sample?
3.A stock solution of phosphoric acid is 85.0% (m/v) H3PO4 in water. What is its molar concentration?
4.Cytosol is an intracellular solution containing many important solutes.Research this solution. Write a paragraph describing the function of cytosol, and the solutes it contains.