"Crystal Phenomenon" Solution PPT Courseware 2

Description

"Crystal Phenomenon" Solution PPT Courseware 2

learning target

1. Understand crystals and crystallization, and have a preliminary understanding of crystallization phenomena;

2. Master the experimental methods for removing insoluble impurities in coarse salt.

1. Crystals and crystallization

How can such beautiful crystals be produced?

Experiment 7-9: Preparation of Alum Crystals

Pour 10 mL of distilled water into one test tube, heat it to boiling, add ground alum crystals until the solids are no longer dissolved, then pour the upper saturated solution into another test tube, and place the test tube in a sink of cold water to cool. Observe the phenomenon.

It can be seen that after the above saturated solution is cooled, crystals precipitate.

The process of forming crystals is called crystallization.

There are two ways to crystallize a solute from a solution

1. Evaporation and crystallization:

Constant temperature evaporation reduces the amount of solvent;

(Suitable for substances whose solubility does not change much with temperature)

2. Cooling crystallization:

Keeping the amount of solvent constant, lower the temperature of the solution.

(Suitable for substances whose solubility decreases significantly as temperature decreases)

2. Application of crystallization method

In actual production, the crystallization method can be used to separate or purify the mixture containing impurities into the substances we need.

Experiment 7-10: Removing poorly soluble impurities from coarse salt

Steps: 1. Dissolve coarse salt

(1) Weighing: Weigh 5.0 g of coarse salt.

(2) Dissolution: Use a graduated cylinder to measure 20 mL of water, pour it into a beaker, add coarse salt to the water, and stir with a glass rod.

2.Filter

Operation precautions

One stick: the filter paper should be close to the inner wall of the funnel;

Second low: ① The edge of the filter paper should be lower than the edge of the funnel

②The liquid level should be lower than the edge of the filter paper

Three leanings: ① The beaker holding the turbid liquid should be close to the glass rod

②The glass rod should be close to the three layers of filter paper

③The lower end of the funnel should be close to the inner wall of the beaker

3. Evaporate

As shown in the picture, place the evaporating dish on the iron ring, pour the filtrate, heat with an alcohol lamp, and stir with a glass rod; when more crystals appear in the evaporating dish, stop heating;

4. Solid salt washing

Use a glass rod to move the solid table salt into a clean filter and rinse evenly with a small amount of water.

summary

1. There are two ways to crystallize a solute from a solution.

(1) Evaporation and crystallization

(2) Cooling and crystallization

2. Remove insoluble impurities in coarse salt

(1) Dissolve coarse salt (2) Filter

(3) Evaporation (4) Solid salt washing

Classic examples

Knowledge point 1: Crystals and crystallization

1. The experimental operations shown in the following figures can crystallize salt in salt water ()

Knowledge point 2: Application of crystallization method

Part of the operation of the coarse salt purification experiment is shown in the figure, the error is ()

Knowledge training

1. To quickly crystallize potassium nitrate from its saturated solution at room temperature, the best method should be ()

A. Cool saturated solution of potassium nitrate

B． Evaporate water at room temperature

C. First heat to evaporate part of the water, then cool down

D． Increase the temperature of a saturated solution

2. Students in the experimental group want to conduct preliminary purification of a coarse salt sample. The experimental instruments or supplies used are as follows:

(1)A’s name is ________;

(2) The steps of purification are: dissolution, filtration, ______;

(3) The key points of the "filtering" operation can be summarized as "one stick, two low, three rely", where the meaning of "two low" is ____________________;

(4)The instrument used in the above three steps is ________.

(5) The salt obtained after purification is ________ (fill in “yes” or “no”) pure product, the reason is ____________________.

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"Crystal Phenomenon" solution PPT courseware:

"Crystal Phenomenon" Solution PPT Courseware New Knowledge Preview 1 Crystals and Crystallization 1. Crystal: Crystals generally have ___________ and have melting and boiling points of ______. 2. Crystallization: The process of forming crystals. Crystals can be formed from ______ solution. After the crystals are precipitated...

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Update Time: 2024-09-09

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

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