Final answer:
pH meter calibration involves major adjustments with a pH 7 buffer and fine adjustments with a pH 4 buffer, followed by titration and recording of pH changes. Dilutions and careful handling of the sensitive electrode are crucial for accurate measurements.
Step-by-step explanation:
Calibrating a pH meter is essential for accurate pH readings. This process involves adjusting the meter to match the known pH values of buffer solutions. Initially, the probe is placed in a buffer with a pH of 7 for major adjustments. Subsequently, a buffer with a pH of 4 is used for fine adjustments. Buffers are carefully prepared, for instance, by diluting a stock solution to achieve the desired concentration in milliliters (ml) using graduated cylinders and pipettes. The pH meter's electrode, especially its glass bulb, must be handled with care due to its fragility. After calibration, titration experiments can be conducted by adding acids like 0.5 M HCl to lower the pH or bases such as 0.1 M NaOH to raise the pH. Taking multiple readings during titration and carefully measuring volumes with a burette ensures accurate plotting of titration curves.
It is crucial to remember that the electrode is highly sensitive and that its functionality directly correlates with the pH of the solution it is immersed in. To maintain accuracy, the electrode should be rinsed with distilled water when moving between solutions and set to standby mode when not in use. For visual pH measurements, pH indicator strips or papers can be used, which change color in response to different pH levels. These colors are then compared to a chart to gauge the solution’s pH. Nevertheless, the digital pH meter provides a more precise reading and is standard in laboratory settings.