"Purification of Water" Water in Nature PPT Courseware 6

Description

"Purification of Water" Water in Nature PPT Courseware 6

Overview: Pure and Natural Water

1. Pure water: It is a colorless, odorless, clear and transparent liquid. Belongs to pure matter

2. Natural water: Natural water such as river water, lake water, well water, and sea water in nature contains many impurities. Insoluble impurities make it turbid, while soluble impurities may give it an odor or color. Belongs to a mixture

Discussion:

1. The river water after heavy rain is very turbid. How to make the turbid river water clear?

2. Water in nature is a mixture and cannot be drank directly. How to turn them into drinking water? What methods do you know?

1. Water purification

1. Water purification process in water plant:

(1) Steps: water collection-precipitation-filtration-adsorption-disinfection-water distribution

(2) Water purification method: precipitation → filtration → adsorption → disinfection

[Explanation] Disinfection is a chemical change, and the rest are physical changes.

2. Purification method:

(1) Precipitation:

1) Leave to settle:

[Principle] Let the water stand for a period of time to allow some insoluble solid impurities in the water to settle. There will be precipitation at the bottom and the water above will become relatively clear.

2) Adsorption precipitation: (flocculant - alum [KAl (SO4)2])

[Principle] The purpose of water purification is achieved by using the colloidal substance formed after alum is dissolved in water to adsorb suspended impurities in the water and settle the impurities.

(2) Filtering:

1) Filtration: It is an operation to separate liquid and insoluble solid substances.

Instruments: filter paper, beaker, glass rod, funnel, iron stand (with iron ring)

2) Key points for filtering operations:

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

Second low: The edge of the filter paper is lower than the edge of the funnel

The liquid level is lower than the edge of the filter paper

Three supports: The mouth of the beaker is close to the glass rod

The glass rod rests lightly on the three-layer filter paper

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

The function of glass rod: drainage

Exchange and discussion

Question 1. What are the possible reasons why the filtrate is still turbid after filtration?

(1) The filter paper is damaged;

(2) The edge of the liquid level is higher than the edge of the filter paper;

(3) The instrument is not clean, etc.

The filtrate that is still turbid should be filtered again until it is clear.

practice

1. Our drinking water is purified from river water. It is known that alum can condense and precipitate suspended solids in the water, and chlorine can sterilize. The correct purification process for household drinking water is ( )

A. River water→filtration→add chlorine→add alum→precipitation→water purification

B． River water→add chlorine→filtration→add alum→precipitate→water purification

C. River water→add alum→add chlorine→filtration→precipitation→water purification

D． River water→add alum→precipitation→filtration→add chlorine→water purification

2. Point out the errors in the picture on the right:

⑴ No glass rod is used for drainage.

⑵The lower end of the funnel is not close to the inner wall of the beaker.

3. What method should be used to remove the following impurities in water:

⑴ Sediment in water: filter.

⑵ Table salt in water: distillation.

⑶ Alcohol in water: distillation.

⑷ Colored and odorous substances in water: adsorption by activated carbon.

problems in life

1. The water in some areas can easily cause scale to form on kettles or water-holding utensils. Why is this?

2. Even if you use water from some areas to wash clothes and put a lot of soap, the clothes still cannot be washed clean?

Exercises and Applications

Fill in the blanks

(1) Alum can be used to purify water because the gel formed by alum dissolved in water can ____ the impurities suspended in the water and make them ____ out of the water.

(2) Water prone to scaling contains more soluble calcium and magnesium compounds, which is called ____ water. This water can be converted into ____ water containing less soluble calcium and magnesium compounds through physical or chemical methods.

practice

1. Which of the following mixtures can be separated by filtration ( )

A. Alcohol and water B. Manganese dioxide and water

C. Salt and sugar D. Iron powder and copper powder

2. After natural water undergoes the following purification operations, soft water will definitely be obtained ()

A. Precipitation B. Filtration C. Adsorption D. Distillation

3. Which of the following methods can distinguish between hard water and soft water ( )

A. Observe the color B. Add alum

C. Dissolve salt D. Add soapy water

4. (2010 Shaoyang High School Entrance Examination) At 07:49 on April 14, 2010, a 7.1-magnitude earthquake occurred in Yushu, Qinghai Province. After the earthquake, the local ecological environment was greatly damaged and the water source was polluted to a certain extent. The daily water used by people in the disaster area must undergo a series of purification treatments before it can be used.

(1) Add alum to the water sample, dissolve, let stand, _______ (fill in the name of the operation) to remove insoluble impurities, then add activated carbon, use its _______ property to remove odors, and then sterilize and disinfect to obtain domestic water.

(2) To determine whether the domestic water obtained is hard water or soft water, _______ can be added for testing. In daily life, ______ is often used to reduce the hardness of water.

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Update Time: 2024-11-24

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