"Amount of Dissolved Substance" Solution PPT Courseware 3

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"Amount of Dissolved Substance" Solution PPT Courseware 3

Preview of new knowledge

1. Saturated solution and unsaturated solution

1. Concept: Under __________, in ____________, a solution that can no longer dissolve a certain solute is called a _______ solution of this solute; a solution that can continue to dissolve a certain solute is called a ______ of this solute. ________ solution.

[Note] (1) When this concept is established, it must be under the premise of "a certain temperature and a certain amount of solvent". (2) A solution that cannot dissolve a certain solute is only a saturated solution of this solute, and may not be a saturated solution for other substances.

2. How to judge saturated solution and unsaturated solution

To determine whether a solution is a saturated solution of a certain solute under certain conditions is to see whether the solute can continue to be dissolved in the solution under the conditions.

2. Mutual conversion of saturated solution and unsaturated solution

The "saturated" and "unsaturated" of a solution only have definite meaning if it indicates "at a certain temperature" and "in a certain amount of solvent". Because under certain conditions, saturated solutions and unsaturated solutions can transform into each other. For most solids:

[Note] For a few substances such as calcium hydroxide, a saturated solution becomes an unsaturated solution when the temperature is lowered, and an unsaturated solution becomes a saturated solution when the temperature is raised.

3. The relationship between saturated solution, unsaturated solution, concentrated solution and dilute solution

1. Saturated solutions and unsaturated solutions are defined based on whether the solute can be ___________ in the solution, while concentrated solutions and dilute solutions are defined based on the amount of solute contained in a certain amount of solution. They are classifications of solutions from different perspectives.

2. For different substances, when the temperature and the amount of solvent are constant, when different substances reach a saturated state, the amount of dissolved solutes will be more or less, and the solutions formed will be either concentrated or dilute, so the saturated solution ________(fill in "certain" or "not necessarily", the same below) is a concentrated solution, and an unsaturated solution __________ is a dilute solution.

3. For the same solute, at the same temperature and in the same mass of solvent, a saturated solution can dissolve more solute than an unsaturated solution, so the ________ solution at the same temperature is more concentrated than the ________ solution.

Interactive exploration

Research point one: Saturated solution and unsaturated solution

[Scenario display]Dissolution of substances in water:

[Question Research]Can soluble substances dissolve in water without limit? How to distinguish between saturated solution and unsaturated solution?

[Inductive improvement] At a certain temperature, the amount of solute dissolved in a certain amount of solvent is limited. Beyond this limit, it cannot continue to dissolve. At a certain temperature and in a certain amount of solvent, a solution that can no longer dissolve a certain solute is called a saturated solution of the solute; a solution that can continue to dissolve a certain solute is called an unsaturated solution of the solute.

[Application Example]

Example 1: On a hot summer day, Xiaolin opened the refrigerator and took out a cup of solution A with a small amount of sucrose solids at the bottom from the storage room at 4°C. After leaving it at room temperature for a period of time, he found that the solids disappeared and obtained solution B. Which of the following statements is correct ()

A． At 4°C, solution A must be a saturated solution

B． At room temperature, solution B must be a saturated solution

C. The solubility of sucrose solids decreases with increasing temperature

D． At 4°C, through constant stirring, the sucrose solids in solution A can also disappear

[ Analysis The solubility of sucrose increases as the temperature increases; stirring can only change the rate of dissolution, but not the solubility of the substance.

[Method call]

(1) When there is no solid solute in the solution, the corresponding solute can be added to the solution to see whether the added solute is dissolved. If it dissolves, the original solution is an unsaturated solution; if it does not dissolve, the original solution is a saturated solution.

(2) When there is a solid solute in the solution, it depends on whether the solid solute continues to dissolve. If it continues to dissolve, it means that the original solution is an unsaturated solution; if it does not dissolve, the original solution is a saturated solution.

Research point 2: Mutual conversion of saturated solution and unsaturated solution

[Scenario display]Interconversion of saturated potassium nitrate solution and unsaturated solution:

[Question Exploration]How to realize the conversion of saturated solution and unsaturated solution? Can a saturated solution be converted into an unsaturated solution by increasing the temperature?

[Inductive improvement] Adding solute and evaporating the solvent at constant temperature will definitely convert the unsaturated solution into a saturated solution. Adding solvent will definitely convert the saturated solution into an unsaturated solution; most solid substances will change from saturated solution to saturated solution when the temperature rises. It is an unsaturated solution, except for a few substances, such as calcium hydroxide.

[Application Example]

Example 2 The most reliable and simplest way to turn an unsaturated solution into a saturated solution is ()

A． Lower the temperature B. evaporate solvent

C. Add solute D. increase pressure

[ Analysis .

[Method Tips] Adding solute and evaporating the solvent at constant temperature will definitely convert the unsaturated solution into a saturated solution; adding solvent will definitely convert the saturated solution into an unsaturated solution. Most saturated solutions of solid substances become unsaturated solutions as the temperature is raised, with the exception of a few substances, such as calcium hydroxide.

On-site testing

Knowledge point 1: Saturated solution and unsaturated solution

1. Which of the following statements about saturated solutions is correct ()

A． A solution that can no longer dissolve any solute

B． It must be a concentrated solution

C. There must be solid precipitated solution after cooling

D． A solution in which the conditions remain unchanged and the solute in the solution can no longer be dissolved

[ Analysis solute.

2. At room temperature, put the same mass of two substances A and B into two beakers each containing 100 mL of water to fully dissolve them. The results are shown in Figure 7-2-2.

Which of the following statements is correct ()

A． A solution is an unsaturated solution

B． Solution B is a saturated solution

C. If the temperature is raised, the remaining acetal solids will continue to dissolve.

D． Solution B may be a saturated solution or an unsaturated solution

[ Analysis

Knowledge point 2: Mutual conversion of saturated solution and unsaturated solution

3. It is known that at t°C, 10 g NaCl dissolved in mg water just becomes a saturated solution. At this temperature, add 8 g NaCl to mg water, and the resulting solution is ________ (fill in "saturated" or "unsaturated, the same below) solution; add 2 g NaCl, and the resulting solution is ________ solution; continue Add 2 g of NaCl, and the resulting solution is a ________ solution. The mass of the solution is __________.

4． When 10 g of water is evaporated from 100 g of potassium chloride solution at room temperature, and 3 g of solid precipitate, the original solution is ________(fill in "saturated", "unsaturated" or "unable to judge") solution; the mass of the remaining solution is_ _____ is a ______ (fill in "saturated", "unsaturated" or "unable to judge") solution at this temperature.

[ Analysis Neither the amount of water evaporated nor the amount of solids precipitated is the mass of the solution.

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For more information about the "Amount of Dissolved Substances in Solution" PPT courseware, please click the "Amount of Dissolved Substances in Solution ppt" tab.

"Amount of Dissolved Substance" Solution PPT Courseware 5:

"Amount of Substance Dissolved" Solution PPT Courseware 5 Knowledge Review Knowledge Point 1 Saturated solution and unsaturated solution 1. Concept: At a certain temperature, in a certain amount of solvent, a solution of ______________ is called a saturated solution of this solute; ____________..

"Amount of Dissolved Substance" Solution PPT Courseware 4:

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"Amount of Dissolved Substance" Solution PPT Courseware 2:

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Update Time: 2024-11-19

This template belongs to Chemistry courseware Cantonese Education Edition Ninth Grade Chemistry Volume 2 industry PPT template

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