Прочтите текст про себя (контрольное время чтения — 3 минуты). Types of Solutions
Just as the variables, pressure, volume, and temperature, were used to describe the state or condition of pure gases, liquids, and solids, these and ccrtain other variables must be used to describe solutions. First, some statement must be made about what chemically important constituents are present in the solution to be considered. A solution of ethyl alcohol (C2H5OH) and water really contains three elements: hydrogen, oxygen and carbon. However, because there is a quantitative relationship (the law of definite composition) between the amounts of carbon, hydrogen, and oxygen in ethyl alcohol, and a similar relationship between the amounts of hydrogen and oxygen in water, the composition of the solution can be completely described by specifying only the quantities of alcohol and wratcr we used to prepare the solution. The substanccs used to specify the composition of a solution arc known as components. One of the components, usually the one which is present in greatest quantity, is callcd the solvent; any other component is callcd a solute.
There arc many possible types of solute-solvent pairs to be listed later. A mixture of two gases satisfies our definition of a solution, but the properties of gaseous mixtures arc usually treated by Dalton's law and wc shall not consider them here. Other types of solutions that arc important arc:
1) liquid in liquid; 4) liquid in solid;
2) solid in liquid; 5) gas in solid;
3) gas in liquid; 6) solid in solid.
Of these, the first three are common, and the last three, called solid solutions, occur less frequently. Mercury dissolved in zinc, hydrogen gas dissolved in palladium metal, and zinc dissolved in copper arc examples of solutions in which liquid, gas and solid, respectively, arc dissolved in solid. Apart from their mechanical properties, solid solutions do not differ greatly from the solutions of liquids.
Упр. 3. Передайте основное содержание текста в нескольких предложениях.
Упр. 4. Какое слово в тексте означает «помимо, кроме»?
Упр. 5. Найдите в тексте ответы на следующие вопросы:
1. Какие параметры использовались для описания физического состояния всщсств? 2. Как определяется состав раствора? 3. Как описываются составные часта раствора? 4. Что говорится о свойствах газовых смсссй? 5. Какие типы растворов относят к твердым растворам? 6. Чем отличаются твердые растворы от жидких?
Упр. б. Закончите следующие предложения:
1. Pressure, volume, temperature and ccrtain other variables were used... 2. A solution of ethyl alcohol contains... 3. A solvent is... 4. A solute is... 5. The most common types of solutions arc... 6. Solid solutions occur...
Section III
Ex. 1. Make up short dialogues according to the example.
Example: — I don't like lectures on history.
— Why not?
— Prof. N speaks too quickly, I can't always follow him.
Ex. 2. Respond to the following statements:
1. There is a property that allows to distinguish a true solution. 2. The properties of solutions can be understood at the molecular level. 3. Both the solvent and the solute determine the properties of a particular solution.
Ex. 3. Give detailed answers to the questions.
1. What is considered to be a true solvent? 2. Can you give any examples of natural solvents? 3. What kinds of solutions do you know? 4. What is the most familiar type of solutions?
Ex. 4. Discuss the following topics:
1. The Characteristic Properties of Solutions.
2. Similarity and Difference Between Various Types of Solutions.
3. The Laws Describing the Properties of Solutions.