Lab report of pH meter PDF

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Summary

A simple example for lab report reference...

Description

TITLE

OBJECTIVES

Using pH meter

1. To calibrate a pH meter 2. To determine the pH of an unknown sample

APPARATUS AND CHEMICALS

PROCEDURES

APPARATUS : Stationary pH meter CHEMICALS : Buffer solution with standardized pH of 4 Buffer solution with standardized pH of 7 Buffer solution with standardized pH of 10 Unknown solution X

CALIBRATION OF pH METER Experiment is started with calibrating the pH meter. The protective cap is removed from the electrode of stationary pH meter. After the removal, the electrode is rinsed with distilled water. The calibration process is using a coloured solutions with standardized buffers. The calibration is started of with buffer solution pH of 7 .The button of ‘CAL’ is pressed before submerging the electrode into the solution. The electrode is then submerged into the buffer solution with pH of 7. The pH meter is calibrated when the pH result of buffer solution shows the standardized value. The electrode is removed and rinsed with distilled water. Process is repeated with buffer solution with pH of 4 and pH 10. Care must be taken to rinsed the electrode with distilled water after using it.The protective cap is also placed back when process is paused.

USING pH METER Unknown solution X, is prepared. The solution is placed below the electrode of stationary pH meter. The electrode is slowly lowered into the unknown solution until it is fully submerged. The reading is recorded. The sample is removed and the electrode is rinsed with distilled water. The protective cap is placed back to the electrode.

SKU3033 ENVIRONMENTAL CHEMISTRY

RESULT

SOLUTION

pH(TEMPERATURE)

Unknown solution X

5.57 (23.9 ℃)

DISCUSSION

A pH meter is used to determine the acidity or basicity of a solution. The pH scale range from 1 to 14. The neutral pH is at 7 while less than 7 is acidic and more than 7 is base. The result from the experiment of determining the pH of an unknown solution is 5.57 at temperature of 23.9℃. The obtained number is less than 7 which indicates that the solution is acidic. When the pH is lower the H+ ion in the solution is high. The lower the pH, the more acidic the solution is. This is because the H+ ion is higher. The result of determining the pH of an unknown solution is also affected by the errors contributed by the machine or during the experiment. As a precaution, the pH meter is made sure to be frequently calibrated. Frequent calibration will witheld coating and aging of the electrode. Care must also be taken to keep and immersed the electrode in a storage solution. It is to prevent the electrode from dehydrating. This will cause a slower response and eventually lead to complete response failure if electrode is exposed longer in open air. When carrying the experiment, students must also make sure to rinse the electrode with distilled water before and after immersing it into any solutions. This will prevent contamination and keep the result accurate.

CONCLUSION

In conclusion, the pH meter is calibrated with using three different buffer solutions with pH of 4,7 and 10. The pH of unknown solution X is also determined using pH meter which is 5.57. The sample is an acidic solution.

QUESTIONS

1. What is buffer solution? Buffer solution is a solution that have the capability to maintain its pH when a small amount of strong acid or strong base added to the solution.

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SKU3033 ENVIRONMENTAL CHEMISTRY

2. Why you need to calibrate the pH meter with standard pH buffer solution before pH measurement? The pH meter needed to be calibrated with standard pH buffer solution to prevent it from drifting away from its setting. If it happens, the result will be inaccurate thus the result obtained from the experiment is useless.

3. Give an example of acidic and basic buffer solution. An example of acidic buffer solution is lemon and basic buffer solution is cleaning agents.

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