Most people are familiar with pH as an indicator of how acid or alkaline a solution is. The pH scale ranges from 0 pH (very acidic) to 14 pH (highly alkaline).

Calibration is a process that allows the digital pH meter to acknowledge if any piece of testing equipment is performing to its up most of use and discharges any problems that it encounters.

Like any laboratory instrument, pH meters need to be calibrated so that they provide accurate readings.

A Digital pH meter uses an electrode to measure the pH of a solution.

1. Press the mode button to select pH.
   
2. Press the Set-up button twice, then press the    
3.  Enter button to clear the existing standardization
4. Press the STD button to begin the new calibration.
5. Remove the electrode from the bottle of storage solution. Rinse with distilled water.
6. Immerse the electrode in pH 4 buffer, which is pink. Swirl the solution to fully saturate the electrode with buffer.
7. Press the STD button again. After the reading is stable, the meter will return to the Measure screen. Press the STD button again to calibrate with a second buffer solution
8. Remove the solution from the pH 4 buffer and rinse the electrode. Emerse the electrode in the pH 10 buffer and swirl.
9. Press STD again to calibrate with this buffer. The meter will display a calibration slope and return to the Measure screen.

Now the meter sis calibrated and ready to use for measuring the pH of any solution.

This is my method of setting up and calibrating a pH meter.

1. Open Calibration program on the computer. Sensing science laboratory. (Science Configuration)

2. Follow what is on the screen.

3. Set the first condition, this will be the pH of the first buffer solution. A buffer solution is a solution of a known pH

4. Ensure the probe is clean, then insert it into the solution (pH4)

5. Click on the next button when the numbers have settled.

6. Rinse the probe with distilled water, then dry with cotton wool.

7. Do the same with solutions 2 and 3.

8. Click next, disconnect then re connect the sensor.

9. Click ok then set the range.

Select user Calibration, then exit.

I was satisfied with the results I obtained each time I did the experiment. I realised that each time I repeated the course of my experiment, my beaker got cleaner due to the distilled water I put in it. This definitely made my experiment more accurate and the results were almost the same every time.

Calibrating the digital pH meter could have caused misconduct to the readings of my solution.  As I can tell you that the beaker I used was already in contact with another human creature before I used it. Meaning to say that bacteria or any other impurities of any kind may have been left behind in the beaker and due to my account could have not been cleaned out properly.  

Results

The PHS we measured were on tap water.

Our first result was; 7.62

Second result; 7.52

Third result, 7.38

A reason why these results varied slightly could have been due to the impurities in the beaker and chloride in the tap water. This was probably because each time we tested the tap water the beaker was washed out, without doing this the beaker could have contained impurities causing the slight difference in the Ph.