"Dissolution and Emulsification" solution PPT courseware

Description

"Dissolution and Emulsification" solution PPT courseware

learning target

1. Understand the phenomenon of dissolution and know concepts such as solution, solvent, and solute;

2. Be able to name some common emulsification phenomena in daily life;

3. Understand the energy changes accompanying the dissolution of substances.

1. Dissolve

Experiment 1: Understand the dissolution phenomenon

Put a small amount of copper sulfate, sucrose, and fine sand solids into each of the three test tubes, add about 10 ml of water to each, shake thoroughly, and observe the phenomenon.

1. Solution: A homogeneous and stable mixture formed by dispersing one or more substances into another substance.

Solution characteristics: homogeneity, stability.

2. Solvent: A substance that can dissolve other substances.

3. Solute: The substance that is dissolved.

Discussion: In the above experimental investigation, which one is the solution, and what are the solute and solvent in the solution?

think

1. Is a homogeneous and stable liquid necessarily a solution?

No, like water.

2. Are all solutions colorless?

No, like the copper sulfate solution in Experiment 1, it is blue.

3. In the copper sulfate solution obtained in the above experiment, are the components of the solution above the test tube the same as those below?

Same, because the solution is homogeneous.

4. What are the common solutions in daily production and life? Can you identify the solute and solvent?

Such as physiological saline, glucose injection, wine, vinegar, etc.

2. Emulsification

Experiment 2: Emulsification phenomenon

Add 3ml of water and a few drops of vegetable oil to a test tube, shake it and let it sit for a while to observe the experimental phenomenon. Then add detergent dropwise to the test tube, shake it and let it stand to observe the experimental phenomenon.

Emulsion: A mixture of small droplets dispersed in a liquid.

Characteristics of emulsion: non-uniform and unstable.

Common emulsions in life: milk, soy milk.

Note: The mixture of fine sand and water in Experiment 1 is also heterogeneous and unstable, but the mixture formed is not an emulsion but a suspension. Suspension: A mixture of small solid particles suspended in a liquid.

Emulsifier: A substance like detergent that stabilizes an emulsion.

Emulsification: The role played by emulsifiers is called emulsification.

Why can emulsions with detergent added remain stable?

Because detergent has an emulsifying function, it can disperse vegetable oil into countless small droplets instead of gathering into large oil beads, so the emulsion added with detergent can exist stably.

3. Endothermic or exothermic phenomena during dissolution

Experiment 3: Take 3g of sodium chloride, ammonium nitrate and sodium hydroxide and dissolve them in 20ml of water. Observe and record the temperature changes before and after adding the solute.

Why do solutes release or absorb heat when they dissolve?

1. Heat is required to disperse molecules or ions from a solute and diffuse into water.

2. The interaction between solute molecules or ions and water molecules to form hydrated molecules or hydrated ions will release heat.

Note: Different solutes absorb and release heat differently, resulting in different temperature rises and falls of the solution.

Temperature changes during dissolution.

1. Heat is absorbed during the diffusion process > heat is released during the hydration process, and the temperature of the solution decreases.

2. Heat is absorbed during the diffusion process < heat is released during the hydration process, and the temperature of the solution increases.

3. Heat is absorbed during the diffusion process = heat is released during the hydration process, and the solution temperature remains unchanged.

Classic examples

Knowledge point 1: Dissolution

Which of the following statements about solutions is correct ( )

A. The solvent must be water

B. There can only be one solute in the solution

C. Colorless and transparent liquid must be a solution

D. The properties of each part in the solution are the same

Knowledge point 2: emulsification

Oil, salt, sauce and vinegar are commonly used condiments. The following condiments are mixed with water to form an emulsion ( )

A.Peanut oil B.Salt

C.Soy sauce D.White vinegar

Knowledge point 3: Endothermic or exothermic phenomenon during dissolution

When the following substances are put into water, the temperature of the solution will drop significantly ( )

A. Concentrated sulfuric acid B. Ammonium nitrate

C.Calcium oxide D.Sodium hydroxide

Knowledge training

1. Solutions are common substances in nature. Which of the following statements about solutions is correct ( )

A. The concentration of the upper layer of the solution is small and the concentration of the lower layer is high.

B. After the solution is evaporated to dryness, solid solute can be obtained

C. When there is only one solute in the solution, the solution is pure

D. During the process of dissolving a substance into a solution, there is usually exothermic or endothermic phenomena.

2. Which of the following substances can form a solution when put into water ( )

A. Flour B. Milk

C.salt D.vegetable oil

3. It is difficult to clean clothes stained with iodine. The solubility of iodine in the following four different solvents is shown in the table below:

Judging from the information provided in the table, the best choice for cleaning iodine stains on clothes is ( )

A.Water B.Alcohol C.Gasoline D.Benzene

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Update Time: 2024-10-03

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

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