Introduction to the properties and uses of hydrochloric acid

One. Learning objectives

1． Recognize the main properties of hydrochloric acid (concentrated hydrochloric acid is highly volatile);

2． Learn about the uses of hydrochloric acid.

3． Through the study of hydrochloric acid properties, we recognize the universality and particularity of things.

Two. Focus on the difficulty

The nature of hydrochloric acid, the control of variables in the exploration experiment and the design of the control group.

Three. Review Consolidation: What are the common oxides that are alkaline in the classification of substances? What is the relationship between metal oxides and alkaline oxides?

1． What is an acid? 2． The concept of sour root? 3． What is alkali? 4． How to distinguish between acid and alkali?

Four. Classroom exploration of the nature of (i) hydrochloric acid

1． Learn about hydrochloric acid (the teacher shows a bottle of concentrated hydrochloric acid)

Activity 1: (Highlighting volatility in hydrochloric acid personality)

（1）． Observe the label of the hydrochloric acid reagent bottle (prompting attention to observe the concentration), observe the color and state of hydrochloric acid.

（2）． Open the cap of the bottle with concentrated hydrochloric acid, observe the phenomenon that occurs at the mouth of the bottle, and fan it with your hand, smell the smell, the bottle mouth appears, which is a small droplet of hydrochloric acid; and there is an odor.

Reflection 1: How is white fog formed?

Concentrated hydrochloric acid is volatile. It can volatilize hydrogen chloride gas. Hydrogen chloride gas encounters water vapor in the air, forming small droplets of hydrochloric acid, so a white mist phenomenon occurs.

From the above phenomenon, we can conclude that concentrated hydrochloric acid is sexual.

Explanation supplement: Hydrochloric acid is an aqueous solution of hydrogen chloride gas that belongs to the mixture. Pure hydrochloric acid is colorless, but industrial hydrochloric acid often appears yellow due to the presence of iron ions.

Reflection 2: What happens if the thick hydrochloric acid is left open?

If concentrated hydrochloric acid is placed open, since concentrated hydrochloric acid is volatile, it will result in both the mass fraction of the solution and the solute in the solution.

Activity 2: (Observe evidence of chemical changes in substances. ）

2. What are the chemical properties of hydrochloric acid

（1）． Hydrochloric acid can react with indicators.

Property 1: It can make the purple litmus test solution turn red, and the colorless phenolphthalein test solution does not change color.

（2）． Reactions to replenish acids and bases: The reaction of sodium hydroxide solution and hydrochloric acid is indicated with purple litmus test solution, and the chemical equation of the reaction of hydrochloric acid and sodium hydroxide is written:.

Reflections: Are there any obvious phenomena in the above reflections? How do I indicate that a substance has a chemical reaction?

Supplementary Thought Questions:

Patients with excessive stomach acid often take baking soda to relieve excessive stomach acidity, but why should patients with stomach ulcers not take baking soda? Instead, it is treated by taking a pill called "gastric shuping", the main ingredient of the pill is aluminum hydroxide, why use it to treat excessive stomach acid? Please use chemical equations to indicate: (1)

（2）

Property 2: Hydrochloric acid can react with alkali to form salt and water. Reaction formula: hydrochloric acid + alkali → salt + water

（3）． Read the textbook P12 page Figure 1-19 (Eggshell and Hydrochloric Acid Reaction) Put the eggshell into a test tube containing hydrochloric acid, and extend the burning wooden strip into the test tube, what phenomenon was observed?.

Complementary experiments: the reaction of sodium carbonate and hydrochloric acid, the gas produced by clarifying lime water, observing what phenomenon?.

The above two reaction equations are required to be written:

A． ；

B． 。

Property 3: Hydrochloric acid can react with salt to generate new salts and new acids. Reaction formula: hydrochloric acid + certain salts→ new acid + new salts

Expanded: Co32-applied testing: With hydrochloric acid, it can produce a gas (carbon dioxide) that makes the clarified lime water turbid.

Zhejiang Edition Textbook P11 page, reaction of hydrochloric acid and silver nitrate.

1． Drop a few drops of silver nitrate solution into a test tube containing a small amount of dilute hydrochloric acid and observe what changes.

Then drop dilute nitric acid and observe its phenomenon

chemical equation:.

2． Drop a few drops of silver nitrate solution into a test tube containing a small amount of sodium chloride solution and observe what happened.

Expansion: This method is commonly used in laboratories to test for the presence of hydrochloric acid or substances capable of ionizing chloride ions (Cl-).

Think: When testing Cl-, why dilute HNO3 solution dropwise?

Supplementary experiment: drop a few drops of AgNO3 solution, and then drop dilute nitric acid, observation?

phenomenon:.

Chemical equation: (1).

（2）。

Conclusion: When testing Cl-, a few drops of dilute nitric acid are added to remove the CO32- interference.

（4）． Read P12 Figures 1-20 (Rust and Hydrochloric Acid Reaction) Add hydrochloric acid to a test tube containing a rusty iron nail, shake, and observe the phenomenon later?

Write the relevant chemical equations according to the phenomenon.

Add hydrochloric acid to a test tube containing a small amount of copper oxide powder, heat it slightly, and observe the phenomenon?

Property 4: Hydrochloric acid can react with metal oxides to form salts and water. Reaction general formula:

Hydrochloric acid + certain metal oxides → salt + water.

（5）． In the above demonstration 2, what other phenomena can be observed in addition to the disappearance of rust?

So is the gas produced by the reaction of hydrochloric acid and metal iron? (Explore experiments, conduct variable control, design control experiments)

①． Establish the hypothesis: Hydrochloric acid reacts with metallic iron to form a gas.

②． Design experiments:

③． Analysis of experimental results:

Fe2O3 is dissolved in A tube, the solution turns yellow, and no bubbles are generated.

Bubbles are generated on the surface of the nail in the B tube.

No bubbles are generated on the surface of the nails in the C tube.

Bubbles are generated on the surface of the zinc particles in the D tube, and bubbles are generated faster than iron.

Property 5: Hydrochloric acid can react with metals to form salts and hydrogen. Hydrochloric acid + reactive metal → salt + hydrogen.

Class Summary: Talk about the chemistry of dilute hydrochloric acid:

Analysis of canonical topics

Example 1 When opening a reagent bottle containing concentrated hydrochloric acid, a white mist appears at the mouth of the bottle. In this regard, it can be concluded that:

（1）

Training Anytime The following description of hydrochloric acid is wrong ( )

A． The solute in hydrochloric acid is HCl

B． Hydrochloric acid can make the litmus test solution blue

C． Human gastric juice contains hydrochloric acid, which helps with digestion

D． Open the cap of the reagent bottle containing concentrated hydrochloric acid, and a white mist appears at the mouth of the bottle

Example 2 Distilled water used in laboratories is seriously contaminated with an acid, and the following methods are used for testing, which are not feasible

Yes ( )

A, take the sample, add Na2CO3 B to it, take the sample, add Ba (NO3)2 to it

C, take the sample, add purple litmus test solution D to it dropwise, take the sample, and add CaCO3 powder to it

Consolidation Training 2 opened the bottle of concentrated hydrochloric acid reagent and found that there was a "white mist" at the mouth of the bottle. Hydrochloric acid is known to contain water molecules (H2O), hydrogen ions (H+) and chloride ions (Cl-). The following experiments can prove that the hydrogen ions contained in the "white mist" are ( )

A.(1)(3) B.(2)(4) C.(1)(2)(4) D.(1)(3)(4)

Tracking Exercise 1: Multiple Choice 1. The following substances are insoluble in water, but soluble in dilute hydrochloric acid is ( )

A． Silver chloride B. Sulfur trioxide C. Iron Oxide D. acetic acid

2． (2014 Liqu) clothes are stained with rust (the main ingredient is Fe2O3), and it is difficult to wash directly with water. To remove rust from a white shirt, the liquid you think is more appropriate is ( )

A． White vinegar B. Soy sauce C. Alcohol D. Dish soap

3． In the experiment shown in the figure, the small beaker (1) contains the purple litmus solution, and (2) contains concentrated hydrochloric acid. After a few moments, it can be observed that the color of the liquid in beaker (1) is ( )

A. Purple B. red

C Colorless D. blue

4． (2021) Add sufficient amounts of the following substances to a certain amount of dilute hydrochloric acid, and the following images can correctly reflect the corresponding change relationship is ( )

A.B.C. D.

5． Dilute hydrochloric acid is a commonly used reagent in chemical experiments, but in the following experiments, dilute hydrochloric acid is not suitable for use is ( )

A. Remove sodium carbonate in sodium chloride solution B. Remove the iron powder mixed in the copper powder

C. Remove limestone from slaked lime D. Remove rust from wire

6． (2021) Place two beakers containing equal mass, equal mass fraction and sufficient amount of dilute hydrochloric acid on the left and right plates of the tray balance, and the balance is balanced. Add 10 g of calcium carbonate to the left plate beaker, and to rebalance the balance, the substance that should be added to the right plate beaker may be ( )

A.10 g potassium carbonate and sodium carbonate B. 10 g magnesium carbonate and sodium carbonate

C.5.6 g copper oxide D. 10 g magnesium powder and copper powder

2. Fill-in-the-blank questions

7． The solution after the reaction of sodium carbonate and dilute hydrochloric acid was added to the phenolphthalein test solution dropwise, and the solution was colorless. The solute that must be contained in the solution after the reaction is; the solute that may be contained is; to check whether it exists, it can be added

。 If observed, it proves the presence of the substance.

8. During the experiment, Xiao Gang put a rusty iron nail into a sufficient amount of dilute hydrochloric acid, and after a while, he saw that the phenomenon was __

After a while, he saw that the rust had completely disappeared and that the surface of the nail had been generated, and the chemical equation for the reaction was ___;

9. Fill a certain quality of concentrated hydrochloric acid in a beaker and place it open in a safe place in the laboratory.

(1) The curve of the relationship between the quality of concentrated hydrochloric acid and the number of days of placement is correct (choose to fill in "A" or "B")

(2) As the number of days of placement increases, the main reason for the change in the quality of concentrated hydrochloric acid is .

(3) Dilution of concentrated hydrochloric acid can be used to remove rust (the main component is Fe2O3) on the surface of iron products, and the chemical equation of the reaction is

10. (2012•Guangzhou) The laboratory has three solutions of hydrochloric acid, white vinegar and citric acid, and answers the following questions:

(1) Put enough hydrochloric acid into the iron trioxide, and after the full reaction, the observed phenomenon is,

The chemical equation for the reaction is .

(2) White vinegar and citric acid solution can also react similarly with ferric trioxide, explaining the vinegar and citric acid solution

And the ions contained in hydrochloric acid are . 21

III. Experimental Inquiry Questions 11. Add sodium hydroxide solution to a beaker containing l0 mL dilute hydrochloric acid (which has a small amount of purple litmus reagent dripped), and determine the pH of the solution with a pH meter (pH measuring instrument), and the data obtained are as follows. Analyze and answer the following questions:

Add the volume of NaOH solution /mL 0 2 4 6 8 10 12 14

The pH in the solution in the beaker is 1.1 1.2 1.4 1.6 2.0 7.0 11 12.2

(1) When the volume of sodium hydroxide solution is mL, dilute hydrochloric acid and sodium hydroxide solution are exactly completely reacted;

(2) When the volume of sodium hydroxide solution is added to 13mL, the solution is colored;

(3) When the pH of the solution in the beaker = 1.4, the solutes in the solution are:

12. Dilute hydrochloric acid can make the purple litmus test solution red. We know that H2O molecules, H+ ions and Cl- ions are present in dilute hydrochloric acid. Would you please design a simple experiment to study the following question: Which particle in dilute hydrochloric acid makes the purple litmus test solution red?

[Your guess]: H+ makes the purple litmus test solution red

The experiment you designed :( steps): .

[Observational phenomena]:.

【Conclusion】: Water molecules can not make the purple litmus test solution red, chloride ions can not make the purple litmus test solution red, H+ makes the purple litmus test solution red.

Attached is a reference answer:

Example 1 (1) Concentrated hydrochloric acid has volatile concentrated hydrochloric acid has volatility (2) HCl is easily soluble in water Analysis: According to the phenomenon of "when opening the reagent bottle containing concentrated hydrochloric acid, a white mist appears at the mouth of the bottle", concentrated hydrochloric acid has a strong volatility, and the volatile hydrogen chloride gas encounters the water vapor in the air to form small droplets of hydrochloric acid. Therefore, the answer is: (1) concentrated hydrochloric acid is volatile; (2) HCl is very soluble in water

Consolidation Training 1 B

Example 2 B

Consolidation Training 2D Analysis: The white mist at the mouth of the thick hydrochloric acid bottle is a small droplet of hydrochloric acid formed by the combination of concentrated hydrochloric acid volatilized hydrogen chloride gas and water vapor.

(1) The litmus test solution turns red when it encounters an acidic solution, so the surface dish coated with purple litmus will turn red when it comes into contact with the "white mist", which can prove that the "white mist" is acidic, which can indicate that the solution contains hydrogen ions;

(2) The surface dish coated with silver nitrate solution will form a white precipitate of silver chloride when it encounters white mist, which can be explained that the fog contains chloride ions, and the existence of hydrogen ions cannot be proved;

(3) The pH test strip can measure the pH of the white mist, so that the white mist (small droplets of hydrochloric acid formed by the combination of hydrogen chloride and water vapor in the air) are acidic, which can prove the existence of hydrogen ions;

(4) Sodium hydroxide can make the phenolphthalein test solution red, so the surface dish coated with sodium hydroxide and phenolphthalein is red, and the small droplets of hydrochloric acid can react with sodium hydroxide, so that the alkaline disappearance of the solution disappears and the red fades, thus proving that the "white mist" is acidic and contains hydrogen ions;

Observe the option to get the answer. Therefore, D. HCl is extremely soluble in water