"Changes in the Solubility of Substances" Dissolution of Substances PPT Courseware

Description

"Changes in the Solubility of Substances" Dissolution of Substances PPT Courseware

Observe and think

Experiment 1. Heat two test tubes containing saturated solutions of potassium nitrate and table salt respectively (both with a certain amount of dissolved solid at the bottom) over the flame of an alcohol lamp and observe the phenomenon; stop heating and cool to room temperature, then put the test tubes into Cool in ice water and observe the phenomenon.

Phenomenon: After heating, the solid dissolves. After the temperature decreases, potassium nitrate and sodium chloride precipitate from the solution respectively, and more potassium nitrate precipitates.

Experiment 2. Heat a test tube filled with saturated clear lime water slightly on an alcohol lamp (no need to boil) to observe the phenomenon.

Phenomenon: A small amount of Ca(OH)2 precipitates in saturated clear lime water

In conclusion

Please summarize the effects of temperature on the solubility of the above substances based on the experimental phenomena, and share your ideas with your classmates.

It can be seen from experimental phenomena that the solubility of solid substances changes with temperature, and the conditions vary with temperature.

For example: saturated potassium nitrate and sodium chloride solutions can continue to dissolve potassium nitrate and sodium chloride as the temperature increases, but a small amount of Ca(OH)2 precipitates in saturated clear lime water.

When the temperature drops, potassium nitrate and sodium chloride precipitate from their saturated solutions respectively, and more potassium nitrate precipitates.

Practice and Application

Draw the solubility curve of potassium nitrate

1. Measure the maximum amount of potassium nitrate dissolved in 100g of water at different temperatures and obtain the following results (table below)

2. Taking the solubility of potassium nitrate as the ordinate and temperature as the abscissa, mark the relationship between the change of the solubility of potassium nitrate with temperature in the following coordinate system.

3. Connect the points in the figure with a smooth curve.

discuss:

The solubility of solid substances is affected by temperature changes:

The solubility of most solid substances increases with temperature, such as potassium nitrate, etc.

The solubility of a few solid substances is not greatly affected by temperature, such as table salt.

The solubility of very few solid substances decreases with increasing temperature, such as hydrated lime.

Let’s talk about: What information can be obtained from the solubility curve?

1: Solubility of the same substance at different temperatures.

2: The relative solubility of different substances at the same temperature.

3: Solubility of substances

Give it a try:

Solubility curve of solid:

1. The intersection point B of the two curves indicates: at 68°C, the solubilities of potassium nitrate and sodium nitrate are equal, both are 133g.

2. At 40°C, the solubility of potassium nitrate ____ (fill in greater than or less than) the solubility of sodium nitrate.

3. At 80°C, the solubility of sodium chloride, potassium chloride, ammonium chloride, and boric acid in descending order is _____________.

Summary and summary

The solubility of gas in water is not only related to the properties of the gas, but also external factors such as pressure and temperature will also affect its solubility.

When the temperature remains constant, gas solubility generally increases as the pressure increases and decreases as the pressure decreases.

When the pressure remains constant, gas solubility generally decreases as the temperature increases and increases as the temperature decreases.

Think about it:

1. Methods to increase the solubility of carbon dioxide in water ( )

A. Warming up and pressurizing; B. Warming up and reducing pressure; C. Cooling down and pressurizing; D. Cooling and reducing pressure.

2. In the sultry summer, most of the fish in the pond float on the water. The reason for this phenomenon is ( )

A. Fish in summer especially like to be on the water surface

B. The water temperature is high in summer, so fish can stay cooler on the water surface.

C. In summer, the water temperature is high and there is less dissolved oxygen in the water, so fish float on the water.

D. In summer, the water surface is particularly rich in nutrients, and fish swim to the surface.

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Update Time: 2024-08-06

This template belongs to Chemistry courseware Hunan Education Edition Ninth Grade Chemistry Volume 1 industry PPT template

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