Part 3

Summary

This lab experiment explores the reactions of copper(II) sulfate with ammonia and hydrochloric acid, emphasizing the importance of conducting the procedure in a fume hood due to hazardous vapors. The experiment begins with the addition of copper(II) sulfate solution, noting its pale blue color and clarity. Upon adding ammonia solutions, distinct color changes occur, leading to a dark blue hue and eventual precipitation. The addition of hydrochloric acid reverses the process, restoring the pale blue clarity. This investigation highlights the fascinating interactions of copper complexes and the effects of pH on their behavior.

Takeaways

• 🧪 Lab safety is important; conduct experiments in a fume hood due to potentially hazardous vapors.
• 🔬 Start the experiment with clean and dry test tubes and holders.
• 🧪 Use a 0.1 M copper(II) sulfate solution for the experiment.
• 💧 The initial copper(II) sulfate solution is pale blue and clear with no precipitates.
• 💧 Adding 2-3 drops of 1 M ammonia solution creates a cloudy solution while maintaining a pale blue color.
• 🌈 The solution turns dark blue after adding 2-3 drops of 15 M ammonia solution, with no visible precipitates.
• 💧 Adding 2-3 drops of 6 M hydrochloric acid changes the color back to pale blue, but the solution remains cloudy.
• 💧 It may take more than 2-3 drops of hydrochloric acid to observe the color change fully.
• 🔍 Observations of color changes are crucial for understanding the reactions occurring in the experiment.
• 📊 The experiment demonstrates the effects of various solutions on the color and clarity of copper(II) sulfate.

Q & A

Why should the experiment be conducted inside a fume hood?

The experiment should be conducted inside a fume hood because some vapors might form that are hazardous to breathe.

What materials are needed for this part of the experiment?

The materials needed include a clean and dry test tube, a test tube holder, a 0.1 molar copper(II) sulfate solution, a 1 M ammonia solution, a 15 molar ammonia solution, and a 6 molar hydrochloric acid solution.

What is the initial observation of the copper(II) sulfate solution?

The initial observation of the copper(II) sulfate solution is that it is a pale blue color and clear, with no precipitates present.

What happens when 2-3 drops of 1 M ammonia solution are added?

When 2-3 drops of the 1 M ammonia solution are added, the solution becomes cloudy, and a precipitate is present, but it remains a pale blue color.

What color does the solution turn after adding 15 M ammonia solution?

After adding the 15 M ammonia solution, the color of the solution changes to dark blue, and there should be no precipitates visible.

How does the solution change after adding hydrochloric acid?

After adding hydrochloric acid, the solution color changes back to a pale blue, but it may still be slightly cloudy.

Is it necessary to add more than 2-3 drops of hydrochloric acid to observe a color change?

Yes, it may be necessary to add more than 2-3 drops of hydrochloric acid to observe the change in color.

What is the final observation after adding hydrochloric acid?

The final observation after adding hydrochloric acid is a clear and pale blue solution.

What should be noted about the clarity of the solutions throughout the experiment?

Throughout the experiment, the clarity of the solutions changes: it starts clear, becomes cloudy with the addition of ammonia, and returns to clear with hydrochloric acid.

Why is it important to note the color and clarity of the solutions at each step?

It is important to note the color and clarity of the solutions at each step to understand the chemical reactions occurring and to identify any precipitates formed during the experiment.