#QUÍMICA - MEDINDO PH COM PHMETRO

Summary

In this video, we demonstrate how to measure pH using a pH meter. The process involves understanding the essential components, including the selective electrode and temperature sensor. Special care is required when handling the electrode, especially keeping its glass tip hydrated. Calibration is crucial, with the electrode being immersed in pH buffer solutions to ensure accuracy. After calibration, the electrode is used to measure the pH of an unknown solution. The video emphasizes the importance of electrode care, proper calibration, and correct technique to obtain reliable pH measurements.

Takeaways

• 😀 Always ensure the electrode's sensitive glass part is kept hydrated and protected from contact with surfaces.
• 😀 The pH meter electrode should be stored with its tip immersed in a potassium chloride solution to maintain its function.
• 😀 When using the pH meter, it’s essential to power it on several minutes before use to allow stabilization.
• 😀 Before measuring pH, the electrode must be calibrated with known buffer solutions to ensure accuracy.
• 😀 The pH electrode should be carefully cleaned with distilled water and dried before calibration or measurement.
• 😀 When inserting the electrode into a solution, ensure the junction (salt bridge) is fully submerged for accurate readings.
• 😀 Calibrate the pH meter with at least two buffer solutions, typically pH 7 and pH 4, for reliable results.
• 😀 If the salt bridge is not submerged in the solution, the measurement will be unreliable.
• 😀 When measuring unknown solutions, rinse the electrode again with distilled water to avoid contamination.
• 😀 After taking a pH measurement, allow a few seconds for the reading to stabilize before recording the result.

Q & A

What is the purpose of using a pH meter in this demonstration?

The pH meter is used to measure the pH level of a solution by detecting the concentration of hydrogen ions in the solution.

What type of electrode is used in the pH meter?

A selective electrode, specifically a glass electrode, is used in the pH meter. It is sensitive to the concentration of ions in the solution.

Why is the glass electrode described as fragile?

The glass electrode is fragile because its sensitive part, which detects ion concentration, is made of thin glass that can break easily.

Why is it important to keep the electrode hydrated?

The glass electrode has a special layer on its surface that needs to remain hydrated for accurate measurements. If it dries out, it can affect its performance.

What solution should the electrode be kept in when not in use?

The electrode should be stored in a potassium chloride solution with a concentration that matches the internal solution of the electrode, typically 3 mol per liter.

What is the procedure for calibrating the pH meter?

To calibrate the pH meter, the electrode is first washed with distilled water, then immersed in a known pH buffer solution. The meter is calibrated using at least two different buffer solutions, such as pH 7 and pH 4.

How should the electrode be handled during calibration?

The electrode should be handled with care by avoiding direct contact with the sensitive part, and it should be immersed properly in the buffer solution, ensuring the salt bridge is covered by the liquid.

Why is the salt bridge important in a pH electrode?

The salt bridge, which is a porous junction between the internal and external solutions, is crucial for maintaining the electrical contact between the two solutions, enabling accurate pH measurements.

What should be done before measuring the pH of an unknown solution?

Before measuring the pH of an unknown solution, the electrode should be washed with distilled water, dried carefully, and then immersed in the solution to be measured.

How is the pH value determined after immersing the electrode in the unknown solution?

Once the electrode is immersed in the solution, the pH value is indicated directly on the pH meter after a few seconds, allowing the value to stabilize for an accurate reading.