"Removal of Insoluble Impurities in Coarse Salt" Salt Fertilizer PPT Courseware 3

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"Removal of Insoluble Impurities in Coarse Salt" Salt Fertilizer PPT Courseware 3

【Thinking 1】

Coarse salt contains soluble impurities (MgCl2, CaCl2, etc.) and insoluble impurities (sediment, etc.). To initially purify coarse salt, what method can be used to remove the insoluble impurities - sediment?

【Thinking 2】

1. What are the steps for purifying crude salt (removing insoluble impurities)?

2. What issues should be paid attention to in each step?

1. Dissolve

Recall the use of scales:

(1) Place it on a horizontal table

(2) Adjust the left balance nut

(3) Weighing objects on the left and weight on the right

(4) Reading m object = m weight + m travel code reading

[Thinking 3] What should we pay attention to during dissolution operation?

1. It is not advisable to add too much coarse salt at one time to avoid adding too much salt and not being able to dissolve it.

2. When dissolving and stirring, the glass rod should be controlled and try not to touch the wall of the beaker.

2. Filter

One sticker: The filter paper sticks to the inner wall of the funnel

Second low

①The edge of the filter paper should be lower than the edge of the funnel;

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

Three things to rely on:

① When filtering, the glass rod should be placed against the side with three layers of filter paper.

②The mouth of the beaker should be close to the glass rod;

③The lower end of the funnel should be close to the inner wall of the beaker to prevent droplets from splashing.

Want to discuss

After filtering the crude salt solution, if the filtrate is still turbid, what might be the reason?

1. The filter paper is damaged.

2. The filtrate is higher than the edge of the filter paper.

3. The beaker that receives the filtrate is not clean (contains impurities).

[Thinking 4] What should we pay attention to during evaporation operation?

1. The evaporating dish should be placed on the iron ring and heated with an alcohol lamp. When heating is stopped, do not place the evaporating dish directly on the experimental table immediately to avoid scalding the experimental table.

2. During the heating process, use a glass rod to stir continuously to prevent droplets from splashing due to excessive local temperature.

3. When more solids (crystals) appear in the evaporating dish, stop heating and use the residual heat to evaporate the filtrate to dryness.

Summary: Steps for purifying coarse salt:

Dissolve:

Filtering: Key points of filtering (one post, two low and three depend)

Evaporation: (Do I need to evaporate all the water before extinguishing the alcohol lamp?)

Recovery and calculation of yield: mass of purified refined salt/mass of coarse salt x 100%

The glass rod is used 4 times in the operation. What are its functions?

Dissolution: Stirring to speed up the dissolution of salt Filtration: Drainage to prevent liquid from splashing out

Evaporation: Stir to prevent droplets from splashing Calculate yield: Transfer solids

2. Removal of impurities from substances

1. The removal of impurities from substances is also called the purification of substances. Its purpose is to remove a small amount of ___________ from the mixture to obtain a purer substance.

2. Material removal follows three principles:

①No new ___________ can be added during the purification process;

②Do not reduce the purified substances, that is, the added reagents only react with ___________ and not with ___________;

③Easy to separate.

3. A certain salt sample contains a small amount of sand, calcium chloride and magnesium chloride. The following is a flow chart designed by a classmate to extract sodium chloride with coarse salt.

(1) Ask students to discuss their design intentions and fill in the blanks.

(2) Discuss and summarize the principles and basic methods of material impurity removal.

Answer according to the flow chart:

(1) The name of operation I is ___________, the reagent A added is ___________, and the precipitation is ___________;

(2) Write the chemical equation___________ for the reaction between NaOH and impurities;

(3) The reagent B added is ___________, and the purpose is ___________;

(4) The function of the glass rod used in evaporation and crystallization is ___________.

Class exercises

The steps for purifying coarse salt are: , , .

In the experiment of purifying coarse salt, glass rods are used in all three steps. Their functions are (fill in the serial number):

(1) The function of dissolving is ( )

(2) The function of filtering is ( )

(3) The function of evaporation is ( )

A. Stir to accelerate solid dissolution

B. Stir to prevent droplets from splashing

C. Drainage and prevent liquid from splashing out

In the experiment of purifying coarse salt, which of the following operations is wrong ( )

A. After filtering the crude salt solution, if the filtrate is still turbid, it should be filtered again

B. Place the evaporating dish on the iron ring and heat it directly with an alcohol lamp

C. During the heating process, use a glass rod to continuously stir the liquid

D. When all the water in the evaporating dish is evaporated, stop heating.

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For more information about the PPT courseware "Removal of Insoluble Impurities in Coarse Salt of Salt Chemical Fertilizer", please click on the Removal of Insoluble Impurities in Coarse Salt of Salt Chemical Fertilizer ppt ppt tag.

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Update Time: 2024-11-17

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