Electrolytic dissociation

The title of the Project: Electrolytic dissociation

This virtual laboratory is intended for use in chemistry classes on the following topics:

  • 9th grade. Chapter I. “Electrolytic dissociation”
  • 11th grade. Chapter X. “Acidic and basic solutions”.

Objectives:

  • to understand the key differences between acidic and basic solutions.
  • to explore the properties of strong and weak acids and bases.
  • to grasp the relationship between pH, concentration, and strength of acid-base solutions.

Practical part

This sim can be used to discover the key differences between acidic and basic solutions.

Step 1. Run the simulation. There are two screens: “Intro” and “My Solution”. Let’s start with “Intro”.

The “Intro” screen

Here, you can explore properties of acids and bases, as well as the difference between strong and weak solutions.

Step 2.  The screen shows a beaker with a solution. You can choose from a list of five solutions to investigate.

Step 3. Let’s begin with a strong acid. There’s a magnified microscopic view of the solution. You can compare this view with a balanced chemical equation to identify the particles shown. The particles are colored to help you see their relative amounts. 

Step 4. Now, generate a list of properties of acids and bases using the simulation tools. Let’s first take a look at the properties of a strong base. The pH of a solution can be determined with a pH meter or pH paper.

Step 5. The conductivity of the solution can be tested with a meter. The amount of light produced by the light bulb helps you compare solution conductivity qualitatively. For example, you could compare the conductivity of this strong base with a weak base or water.

Step 6. This screen can also help you understand how to use the terms “strong” and “weak” when describing acids or bases. Let’s start with a strong acid. You can use the graphical representation to see the amounts of undissociated acid, conjugate base, and hydronium ions in the solution.

Step 7. Then, select a weak acid and note any changes in the equilibrium concentrations of the undissociated acid and conjugate base.

Step 8. Once you have developed a definition of strong and weak acids, you can use the simulation to test and refine your definitions by comparing strong bases and weak bases.

The “My solution” screen

In this screen students can experiment with creating acid and base solutions to understand the difference between their strength and concentration.

Step 9. This screen looks just like the first one and has all the same tools, but here’s the cool part: you can build your own solutions! This lets you play around with different starting concentrations and acid strengths to see how they affect the solution’s pH.  

Step 10.You can use the My Solution screen to challenge yourself to see how many ways you can create a solution with a particular pH. For example, you might try to create solutions with a pH of 3. Let’s start by placing the pH meter in the solution and choosing the “Graph” view.

Step 11. One way to create a solution with a pH of 3 is to set the strength toggle to “strong” and the initial concentration to 0.001 Molar. You should notice that the acid has completely dissociated and that the concentration of hydronium is 0.001 Molar.

Step 12. To create a weak acid solution with a pH of 3.0, you could increase the initial concentration to 1.0 Molar and move the strength toggle to weak. You could then use the slider to adjust the pH to 3. Notice that although the acid does not completely dissociate, the concentration of hydronium ions is again approximately 0.001 Molar. You could explore additional ways to create solutions with a pH of 3, by varying the initial solution concentration as well as the acid strength.

This exercise challenges the misconception that pH can be used to measure the strength of an acid or a base. It reinforces the idea that pH is a measure of hydronium ion concentration. This challenge also provides an opportunity to learn the appropriate use of the words “dilute” and “concentrated” when referring to acid-base solutions.

Conclusion

This simulation provides a virtual laboratory environment for students to investigate the fundamental concepts of acids and bases. Through interactive exploration, students can discover the unique properties of strong and weak solutions, understand how pH relates to hydronium ion concentration, and differentiate between concentration and strength. By addressing common misconceptions and allowing for experimentation, the simulation fosters a deeper understanding of these essential chemical principles.