"Concentration of Solution" Solution PPT (Lesson 2)

Description

"Concentration of Solution" Solution PPT (Lesson 2), 16 pages in total.

Import new lesson

"Poetry for Cooking Porridge":

"How to cook rice rather than porridge? Discuss it carefully with your children. One liter can be used for three liters, and two days can be used as six days of food. When there are guests, you only need to add water and fire. If you have no money, you don't need to make soup. Don't think that indifference will taste less, and indifference will The taste is long."

After adding water to the porridge, the rice grains remain unchanged and the porridge becomes thinner. If water is added to vegetable soup, the quality of salt in the soup will remain unchanged and the taste of the soup will become lighter. This phenomenon is similar to the dilution of a solution.

learning target

1. Master the calculation of solution dilution and preparation problems;

2. Master the mass fraction of solute and apply it to the calculation of chemical equations.

Teach a new lesson

[Example 1] Put 1 g of table salt into a beaker, add 9 mL of water, and stir with a glass rod until dissolved. Then add 10 mL of water to the above beaker and stir. (The density of water is 1 g/cm3)

1. Try to write down the solute mass, solution mass, and solute mass fraction before and after dilution.

2. Analyze the changes in each quantity. What is the key to solving solution dilution problems?

1. Before dilution, the solute mass is 1 g, the solvent mass is 9 g, and the solute mass fraction is 10%; after dilution, the solute mass is 1 g, the solution mass is 20 g, and the solute mass fraction is 5%.

2. After dilution, the mass of the solution increases, the mass fraction of the solute decreases, and the mass of the solute remains unchanged.

[Example 2] The chemistry laboratory currently has 98% concentrated sulfuric acid, but in experiments it is often necessary to use dilute sulfuric acid solutions. How many grams of water are needed to dilute 50 g of concentrated sulfuric acid with a mass fraction of 98% into a sulfuric acid solution with a mass fraction of 20%?

Solution 1: Suppose the mass of water to be added is x.

50 g×98%=(50 g+x)×20%,

x=195g.

Answer: To dilute 50 g of concentrated sulfuric acid with a mass fraction of 98% into a sulfuric acid solution with a mass fraction of 20%, 195 g of water must be added.

Class summary

1. Calculation of solution dilution and preparation problems

Key: Mass of solute before dilution = Mass of solute after dilution When volume is involved:

Mass of solute = volume of solution × density of solution × mass fraction of solute

2. The mass fraction of solute should be used in the calculation of chemical equations. It is the solute in the solution that participates in the chemical reaction.

Keywords: Free download of PPT courseware for the second volume of the ninth grade of Chemistry published by the People's Education Press, PPT download of the concentration of the solution, PPT download of the solution, .PPT format;

For more information about the "Concentration of Solution" PPT courseware, please click on the "Concentration of Solution PPT" PPT tab.

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Update Time: 2024-11-08

This template belongs to Chemistry courseware People's Education Press Ninth Grade Chemistry Volume 2 industry PPT template

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