"Purification of Water" Water in Nature PPT Courseware 5

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"Purification of Water" Water in Nature PPT Courseware 5

1. Natural water

How to deal with impurities in water?

Domestic water in cities is purified and treated by water plants.

Classification of water

Pure water: (Pure substance) Colorless, odorless, clear and transparent liquid.

Natural water: (Mixture) Natural water such as river water, lake water, well water, sea water, etc. contains impurities.

Insoluble impurities make water cloudy

Soluble impurities may give water an odor or color

Standing and settling: After letting the water stand for a period of time, there will be precipitation at the bottom and the water above will become relatively clear.

Adsorption and precipitation (water purification effect of alum)

Experiment 4-1: Take 2 beakers, each containing half a cup of turbid natural water, add 3 spoons of alum powder to 1 of the beakers, stir and dissolve, then let it stand and observe the phenomenon.

Filtration: A method of separating solid substances that are insoluble in liquids from liquids

Discussion: (1) In the above filtration experiment, what are the key operating points?

One sticker: The filter paper should be close to the inner wall of the funnel.

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

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

Three supports: The mouth of the beaker should be close to the glass rod for drainage;

The lower end of the glass rod should rest against one side of the three layers of filter paper;

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

Please think carefully before answering:

1. The filter paper must be tightly attached to the funnel without leaving any air bubbles (why?)

If there are bubbles, the filtration speed will be slower.

2. The edge of the filter paper is lower than the edge of the funnel (why?)

Prevent liquid from flowing out of the funnel

3. Is the filtered water pure water? no

4. What impurities are mainly removed from water by filtration operation? Remove insoluble impurities

[Summary] Methods to remove insoluble impurities: precipitation and filtration.

[Question] What are the possible reasons why the filtrate is still turbid after filtration?

(1) The filter paper is damaged;

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

(3) The instrument is not clean, etc.

At this time, if the filtrate is turbid, it should be filtered again until it is clear.

Question: The filtered water is clear but red. How to remove color?

Think about it:

Have you ever observed the inside of a kettle or thermos that has been used for a long time?

Have you ever used a lot of soap but couldn't get any lather?

Have you ever worn clothes that feel stiff after being washed?

Instructions for use of Tide laundry detergent: "Suitable for hand washing, machine washing, hard water, and soft water."

2. Softening of hard water and testing methods

1. Hard water and soft water:

Hard water: water containing more soluble calcium and magnesium compounds

Soft water: water with no or less soluble calcium and magnesium compounds

2. Testing methods for hard and soft water: soapy water

Hard water - easy to scum (less foam, more scum)

Soft water - more foam (more foam, less scum)

3. Dangers of hard water

⑴ Waste of fuel and prone to accidents. For example: boiler scaling may cause explosion risk

⑵ Drinking hard water for a long time can easily cause stones.

⑶ Waste of detergent, the washing will not be clean and the clothes will become hard.

⑷With long-term irrigation use, soluble salts will be deposited in the soil, leading to increased soil salinization.

4. Softening of hard water:

Industry - ion exchange method and pharmaceutical method

In life - boiling

Laboratory - Distillation

practice

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

A. Alcohol and water B. Salt and sediment

C. Salt water D. Iron powder and copper powder

2. After the 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

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For more information about the PPT courseware "Water Purification of Nature's Water", please click on the "Water Purification ppt Nature's Water ppt" tag.

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Update Time: 2024-10-17

This template belongs to Chemistry courseware People's Education Press Ninth Grade Chemistry Volume 1 industry PPT template

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