"Acidity and Alkalinity of Solutions" Common Acids, Alkalis, and Salts PPT Courseware 3

Description

"Acidity and Alkalinity of Solutions" Common Acids, Alkalis, and Salts PPT Courseware 3

learning target

1. Learn to distinguish between acidic solutions and alkaline solutions

2. Ability to use acid-base indicators to qualitatively test the acidity and alkalinity of solutions

3. Be able to use pH test paper to quantitatively measure the pH of a solution

4. Know the pH of common substances and the impact of pH on life activities

1. Distinguish between acidic solution and alkaline solution

What substances in life leave a "sour" impression on you?

What substances in life have left an "alkali" impression on you?

Review the past and learn the new:

Carbonic acid can turn purple litmus solution red

Ammonia can turn colorless phenolphthalein test solution red

Experimental Activity 1: How to distinguish the acidity and alkalinity of solutions

content:

Use 4 test tubes to take two parts each of hydrochloric acid solution and lime water, then take litmus solution and phenolphthalein solution and drop them in different test tubes to observe the color.

Experimental Activity 2: Distinguish the acidity and alkalinity of different solutions

Design similar experiments using different substances as shown in the figure below to distinguish their acidity and alkalinity.

Through the above experiments, the following conclusions are drawn:

Acidic solutions can turn litmus test solution red but not phenolphthalein solutions; alkaline solutions can turn litmus test solution blue but phenolphthalein solutions turn red.

Substances such as litmus and phenolphthalein that can react with acid or alkali solutions to display different colors are called acid-base indicators.

For convenience of use, blue or red litmus paper is usually used to test the acidity and alkalinity of the solution.

1. Acidic solution turns blue litmus paper red;

2. Alkaline solution turns red litmus paper blue.

How to use litmus paper: Place the litmus paper on a watch glass, use a glass rod to dip a small amount of sample solution onto the litmus paper, and then observe the change in color of the test paper.

2. Test the acidity and alkalinity of the solution

Expression of the acidity and alkalinity of a solution - pH

The acidity and alkalinity of a dilute solution is often measured by the pH of the solution, which is expressed as the pH of the solution.

The pH range of the solution is generally between 0 and 14. At room temperature:

Acid solution pH＜7

Neutral solution pH=7

Alkaline solution pH>7

The more acidic the solution, the lower the pH; the more alkaline the solution, the higher the pH.

The easiest way to measure pH: use pH test paper

When measuring, place a piece of pH test paper on a glass piece or white porcelain plate, use a glass rod to dip the solution to be measured and drop it on the pH test paper. After half a minute, compare the color displayed on the test paper with the standard color card to get the solution. pH.

Notice:

(1) Do not immerse the pH test paper directly into the solution to be tested to avoid bringing in impurities and contaminating the test solution. At the same time, this operation may soak away part of the indicator on the pH test paper, causing a large error in the colorimetry;

(2) You cannot wet the pH test paper with water before testing, because the pH test paper moistened with water will dilute the solution to be tested, resulting in errors;

(3) The pH test paper generally used in our laboratory is a wide range of pH test paper, and the measured pH value is an integer from 1 to 14;

(4) In order to more accurately measure the pH of a solution, we can use precision pH test paper and an acidity meter (pH meter) to measure it.

Classic examples

Knowledge point 1: Distinguish between acidic solution and alkaline solution

1. Add two drops of purple litmus test solution into a bottle of colorless and transparent solution. If the solution turns the litmus red, it means the solution is ( )

A． Aqueous solution of acid B. Alkaline aqueous solution

C. Alkaline solution D. acidic solution

Knowledge point 2: Test the acidity and alkalinity of the solution

1. The solution pH of some common items in the home, among which the most acidic one is ( )

A． Salt water pH=7 B． Toothpaste pH=9

C. Soap pH=10 D. Vinegar pH=3

Knowledge point 3: pH of common substances

1. The approximate pH range of some common foods is as follows:

Which of the following statements is correct ( )

A． Grape juice can turn phenolphthalein test solution red

B． Tomatoes are more acidic than apples

C. People with hyperacidity should eat less apples

D． Milk is more alkaline than egg white

Knowledge point 4: pH and life activities

1. In order to maintain normal life activities of the human body, the body fluids in different organs of the human body have different acidity and alkalinity. According to the following table, under normal circumstances ( )

A． Human urine must be acidic

B． Human blood must be alkaline

C. Human gastric juice can turn purple litmus solution blue

D． pH test paper can accurately measure the pH of the above body fluids

Knowledge training

1. Which of the following common substances in life can make the colorless phenolphthalein test solution turn red ( )

A． Vinegar b. lemon juice

C. Salt water D. soapy water

2. To determine the pH of a solution, you can use ( )

A． Litmus test b. Phenolphthalein test solution

C. pH test paper D. blue litmus paper

3. Which of the following solutions must be acidic ( )

A． After dropping phenolphthalein, it becomes a colorless solution

B． Solution with pH=13

C. Drop in the litmus test solution that turns red

D． Ammonia solution

4. When using pH test paper to measure the pH of white vinegar, if you first wet the test paper with distilled water and then drop white vinegar onto the test paper, the measured result will be compared with the actual pH of the white vinegar ( )

A． On the low side B. On the high side

C. equal D. Can't compare

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For more information about the PPT courseware "Acidity and Alkalinity of Common Acid, Alkali and Salt Solutions", please click on the acidity and alkalinity of common acid, alkali and salt ppt solutions ppt tag.

"Acidity and Alkalinity of Solutions" Common Acids, Alkalis, and Salts PPT Courseware 4:

"Acidity and Alkalinity of Solutions" Common Acids, Alkalis, and Salts PPT Courseware 4 Knowledge Review Knowledge Point 1 Distinguish between acidic solutions and alkaline solutions To determine the acidity and alkalinity of a solution, you can use _____________. Like litmus and phenolphthalein, they can react with acid or alkali solutions.

"Acidity and Alkalinity of Solutions" Common Acids, Alkalis, and Salts PPT Courseware 2:

"Acidity and Alkalinity of Solutions" Common Acids, Alkalis, and Salts PPT Courseware 2 New Knowledge Preview 1. Distinguish between acidic solutions and alkaline solutions 1. Acid-base indicator: A substance that can react with ______ solution or ______ solution to show _____________ is called an acid-base indicator, or...

"Acidity and Alkalinity of Solutions" Common acids, bases, and salts PPT courseware:

"Acidity and Alkalinity of Solutions" Common Acids, Alkalis, and Salts PPT Courseware Learning Objectives 1. Learn to use two indicators, litmus and phenolphthalein, to test the acidity and alkalinity of solutions. 2. Understand the relationship between the acidity and alkalinity of a solution and the pH of the solution, and be able to use pH test paper to quantitatively measure the pH of the solution. 3..

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Update Time: 2024-10-02

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

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