"Dissolution and Emulsification" Solution PPT Courseware 2

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"Dissolution and Emulsification" Solution PPT Courseware 2

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1. Emulsion, emulsifier, emulsification

1. emulsion

[Conclusion] (1) The mixture formed by small droplets dispersed in a liquid is called __________. For example, a mixture obtained by dropping vegetable oil into water and shaking. (2) Characteristics of emulsion: ________, _______, easy to layer.

[Tips] Milk and soy milk in daily life are all emulsions.

2. Substances like detergents that ___________ are called emulsifiers. The function played by emulsifiers is called _________.

3. Commonly used emulsifiers in daily life include _______________ and so on.

2. Endothermic or exothermic phenomena during dissolution

1. There are ____ changes in the process of substance dissolution: First, the molecules or ions disperse from the solute and diffuse into the water requiring ________ heat; second, the solute molecules or ions react with water molecules to form hydrated molecules or hydrated ions, which will ______ heat. Different solutes absorb and release heat differently, causing the temperature of the solution to rise and fall differently.

2. The temperature of the solution increases due to the heat released during the hydration process______the heat absorbed during the diffusion process. For example: _______________ dissolves in water and causes the temperature of the solution to increase.

3. The temperature of the solution decreases because the heat absorbed during the diffusion process ______ the heat released during the hydration process. For example: _________ dissolves in water, causing the temperature of the solution to decrease.

4. If the heat absorbed by the diffusion process is similar to the heat released by the hydration process, then the temperature of the solution will remain basically unchanged. For example: _________ dissolves in water so that the temperature of the solution remains basically unchanged.

[Application Example]

Example 1 2013·Xiamen Which of the following washing or decontamination processes applies the emulsification principle ()

A. Use gasoline to remove oil stains from clothes

B． Use alcohol to remove iodine from clothes

C. Use dish soap to remove grease from dishes

D． Use a brush to remove dirt from the cup

[ Analysis This effect of dish soap or laundry detergent is emulsification as the water washes away.

[Method Tips] There are three common washing principles: one is to use emulsification. Emulsification is just the emulsifier dispersing large droplets into countless small droplets in the water without aggregation. This phenomenon is called emulsification. Phenomenon; the second is to use the principle of dissolution, which means that the molecules or ions of the solute are uniformly diffused in the solvent; the third is to use chemical reactions between substances and oil stains to convert the oil stains into soluble substances and remove them. Understanding the principles utilized in the washing process is the key to solving the problem.

Example 2 Xiao Ming designed an interesting experimental device (as shown in Figure 7-1-1), which has good air tightness. To produce a "fountain" in the pointed tube in B, the solids and liquids added in A may be ()

A. sodium chloride and water

B． Ammonium nitrate and water

C. sodium hydroxide and water

D． Copper and dilute sulfuric acid

[ Analysis Absorption; sodium hydroxide solid dissolves and releases heat, causing the temperature inside the bottle to rise, causing the pressure inside the bottle to increase, so a "fountain" will be observed; copper and dilute sulfuric acid do not react, so there is no obvious phenomenon.

[Method Instructions] The temperature changes caused by the generation and absorption of gas or the dissolution of substances will cause the pressure in the closed container to change, and then produce obvious phenomena. The endothermic and exothermic phenomena during the dissolution of substances will cause temperature changes, resulting in changes in pressure within the closed device. When a substance dissolves in water, two processes and heat changes occur in the water: a. Diffusion process, that is, the molecules (or ions) of the solute diffuse into the water, which is a physical process that requires the absorption of heat; b. Hydration process, that is, the molecules (or ions) of the solute ( The process of interacting with water molecules to generate hydrated molecules (or hydrated ions) is a chemical change that requires the release of heat. When a substance dissolves, the temperature of the solution increases or decreases depending on the amount of heat absorbed or released in these two processes.

On-site testing

Knowledge point 1: emulsion, emulsifier, emulsification

1. Which of the following substances can form emulsions in water ()

A. SucroseB. Table salt C. flour d. vegetable oil

2. Washing is indispensable in life and production. Which of the following washing methods utilizes the emulsification principle ()

A. Use gasoline to wash away the oil on your hands

B． Use dishwashing detergent to remove oil stains from tableware

C. Wash the iodine out of the test tube with alcohol

D． Use dilute hydrochloric acid to remove rust from the surface of iron products

Knowledge point 2: Endothermic or exothermic phenomenon during dissolution

3. Which of the following groups of substances cannot be identified using water alone ()

A. Salt solid, calcium carbonate solid, potassium permanganate solid

B． Hydrogen, oxygen, carbon dioxide

C. Gasoline, alcohol, concentrated sulfuric acid

D． Sodium hydroxide solid, salt solid, ammonium nitrate solid

[ Analysis , Concentrated sulfuric acid dissolves in water and releases heat. In item D, sodium hydroxide solid dissolves in water and releases heat. Salt solid dissolves in water and the temperature does not change. Ammonium nitrate solid dissolves in water and absorbs heat. Three different phenomena occur when encountering water. Can be identified; hydrogen and oxygen are not easily soluble in water and cannot be identified.

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Update Time: 2024-11-22

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

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