Lesson
Purpose of the work:
- to study the chemical properties of hydrochloric acid solution
Expected results:
After completing the work, students can:
- develop teamwork skills
- be able to analyze and summarize the information received
- draw logical conclusions
Teacher’s Guide:
- The task is performed in groups of 2-3 people
- Before starting laboratory work, please read the safety rules by following the link:
- To download the worksheet, follow the link:
Precautions:
- Work only with diluted hydrochloric acid.
- Carry out all experiments under traction or in a well-ventilated area.
- Use safety glasses and gloves.
- Do not smell or taste the reagents.
- Do not mix acids with other substances without the teacher’s instructions.
Theoretical part
Hydrochloric acid (HCl) is one of the most common and important inorganic compounds. It is a colorless, transparent gas with a pungent odor that is highly soluble in water. Aqueous solutions of hydrogen chloride are called hydrochloric acid.
Significance of Hydrochloric Acid
Hydrochloric acid plays a crucial role in various human activities:
- Industry: Used for metal cleaning, organic compound production, polymer synthesis, and other substances.
- Laboratory work: Employed as a reagent for conducting chemical analyses and syntheses.
- Food industry: Utilized as a food additive (E507) to regulate acidity.
- Medicine: A component of gastric juice, involved in digestion.
Practical part
Step 1. Add 2 ml of hydrochloric acid to each of the test tubes.
Experiment #1: Interaction with indicators
Step 2. Add a litmus indicator to the first test tube. Determine the pH of the solution on a scale.
Step 3. Now add a natural indicator to the same tube. Observe the color changes.
Experiment #2: Interaction with the bases
Step 4. Add the same amount of sodium hydroxide to the second test tube with acid.
Step 5. Check the resulting solution with an indicator.
Experiment #3: Interaction with salts
Step 6. Add a piece of chalk to the next test tube. Observe the changes.
Step 7. On your Worksheet, write down the chemical equation of the reactions and draw conclusions about the work.
Conclusion
The experiments have confirmed the characteristic properties of hydrochloric acid as a strong acid. The observed changes in the color of the indicators, the release of gas during interaction with carbonates indicate a high chemical activity of hydrochloric acid.